The aromatic vineyards of Würzburg and the city’s architectural masterpieces hardly registered with Tyrell Terry as he journeyed to the Franconia region of Germany in December. His life in basketball, once a source of joy to him, had collapsed into a debilitating and lonely loop, and he could see little beyond his own misery. He was venturing nearly 5,000 miles mostly because he needed a friend.

If anything could renew his desire to play basketball, Terry reasoned, it would be joining up with his buddy Nico Carvacho, who now played in a professional league in Germany. Terry had struggled to make friends during his short time in the N.B.A.

Snow dusted the ground as Terry settled into his one-bedroom apartment. Achy with the flu, he labored through a practice with Carvacho and his other new teammates. Then his real symptoms resumed.

In the mornings, he dashed to the bathroom, fell to his knees by the toilet and threw up. His weight plummeted. He lost two pounds. Three. Five. The cycle had come for him again, the same relentless anguish that had drained the enjoyment from his life and stripped away his N.B.A. career.

“Those feelings of enjoying basketball like I thought I did, it just didn’t come back,” Terry recalled later. “And that was all the way across the world.”

After just a couple of practices with his new team, he picked up the iPhone that he rarely used anymore, not even to respond to probing texts from family and friends. Tears filled his eyes as sat back on his sofa and typed.

“This message is a very difficult one to share and an emotional one to write,” he began.

Terry was 22 years old and 6 feet 2 inches, with the kind of wavy hair sweatbands were made for. Once, basketball scouts imagined him as another Stephen Curry. But he wrote that he was letting go of basketball, the game that had taken him to Stanford for one year, and then to Dallas and Memphis in the N.B.A. “Instead of building me up,” he wrote on Instagram, “it began to destroy me.”

He went on: “While I’m grateful for every door it has opened for me, I can’t continue this fight any longer for something I have fallen out of love with.”

Depression and anxiety have become safer topics in the N.B.A. because of the openness of star players like DeMar DeRozan, Kevin Love and Paul George. The phenomenon reaches across professional sports, with young athletes like the tennis player Naomi Osaka, the swimmer Michael Phelps and the gymnast Aly Raisman talking candidly about their struggles. But few have simply quit their sports completely.

So it was striking when Terry, citing “intrusive thoughts” and anxiety, said he was walking away from the game he had once loved and had been paid millions to play.

In interviews over five months — in his hometown, Minneapolis, on the Stanford campus and on the phone — Terry discussed the slow unraveling of his mental health, the fractured relationship with his father that left him feeling unmoored and his desire to shed the identity he had spent a lifetime building.

“I want to be able to completely ditch that part of me,” Terry said.

Back Where He Started

A month after he had abruptly retired from basketball, Tyrell Terry stepped over the ever-present piles of melting snow just outside downtown Minneapolis and ducked inside a Five Guys hamburger restaurant. He was enjoying his days, he said, occasionally lifting weights but mostly hanging out with his longtime girlfriend, Isabelle Florey, and their dog, Touie. He had plans to return to Stanford in April. He called it “a new chapter in my life.”

The first chapter had been in this city, where he grew up and learned to play ball.

His father, Tyron Terry, and his mother, Carrie Grise, met as children in North Dakota and had Tyrell while they were still in college. By the time Tyrell was 4, his parents’ relationship was over, and Grise moved with her son to Minneapolis. His father played basketball at the University of Texas at San Antonio and North Dakota State, but his career stalled after that.

Tyrell grew up troubled by the feeling that he was more a burden than a joy. In time, he would struggle to form strong relationships or keep the ones he had.

“I was aware at an early age of the fact that if I wasn’t born, it would probably have been a lot easier for my parents,” Tyrell said. “Maybe my dad goes further in basketball. It wouldn’t have been so hard for my mom to finish her degree.”

But he was also remarkably gifted. In Minnesota, Terry joined a basketball team started by Grise’s former classmate Larry Suggs. Terry, Suggs said, “could play basketball in his sleep.”

“He was not always the most confident kid, but you would’ve thought he was that confident kid because he was so good,” he said.

Terry was an excellent student, too, the kind who pestered teachers for extra homework. Once, he asked Suggs if he could skip a basketball game so he could fire a rocket he had made for a science project.

The boys on Suggs’s basketball team enrolled at Minnehaha Academy for middle school, and Terry, the team’s point guard, ran the show. But for years, he felt overshadowed by Suggs’s son, Jalen.

“We were so close, but he had it earlier than I did,” Terry said. “He had the mentality earlier than I did, the confidence, the skill set, the size. People knew from a way earlier age that he was destined for greatness.”

He added, “It was tough for me to always go into the situation as the Robin.”

Terry’s relationship with the Suggses had fractures Larry and Jalen couldn’t see. After the eighth grade, Terry transferred to DeLaSalle High School without talking to them about it. Terry said in an interview that he had been immature and that he had reconnected with Jalen after Jalen joined him in the N.B.A. But at the time, Larry and his son were mystified and hurt.

“Everything that I had known was always with him,” Jalen said, adding that they had talked about attending the same college. “It was hard. It was different. I didn’t completely understand or want to accept it, and to be honest, initially, there was a little resentment.”

Larry Suggs said it had been “very tough.”

“It’s like losing a son,” he said.

‘I Don’t Think I Was Emotionally Ready’

Terry had just turned 19 when he made his debut for Stanford in 2019. Within months of his arrival, some analysts were imagining him as a sharpshooter like Curry, the Golden State Warriors star, or Trae Young of the Atlanta Hawks.

He scored 13 points in his first game and shot with pinpoint accuracy throughout his freshman season, connecting on 40.8 percent of his 3-pointers and nearly 90 percent of his free throws. Stanford Coach Jerod Haase texted him pictures of green lights before one game, letting him know he was free to shoot the ball when he wanted. But the emphasis on shooting felt awkward to Terry. He said he had always taken pride in being a true point guard focused on making timely passes.

He started to wonder whether he should move on. N.B.A. teams were sniffing around, and Terry knew Stanford planned to welcome Ziaire Williams, a top recruit, the next season. Terry said Haase had told him that he couldn’t guarantee him as many shot attempts once Williams arrived.

“I don’t think I was emotionally ready to go to the N.B.A.,” Terry said. “I was still wanting to be a kid, still wanting to be at college with my friends. But I don’t regret the decision.”

Haase said Terry had been in a “hard spot.”

Terry weighed about 160 pounds, but N.B.A. personnel suggested that he bulk up to survive the league’s physicality. He lifted weights and ate until he felt nauseous. By the N.B.A. draft combine in October 2020 (it was delayed because of the coronavirus pandemic), Terry was 170 pounds and worried that he had not put on enough weight.

The Dallas Mavericks drafted him 31st overall. On draft night, he spoke about meditating and reading books to prepare mentally for the N.B.A. But when the season started two days before Christmas, he felt alone. He was barely 20 and living by himself in Dallas. His father was no longer in his life.

“You’re performing at the highest level every day,” Jalen Suggs said. “Not only for a spot on the team, but for paychecks and for money and for your future and it feels like you’re just constantly chasing that. Life moves really fast. To not have that time to slow down, really process everything and get accustomed to it, it definitely can be difficult for anybody, and it was for me.”

Dallas had well-known players like Luka Doncic, Kristaps Porzingis and Tim Hardaway Jr., but Terry said no veterans had taken him under their wing. (Terry admitted that he had often bolted right after practice, even though coaches had wanted him to stay.)

By March, after a stint in the N.B.A.’s developmental league, he’d had enough. He called the team’s director of psychology. “I just can’t do this anymore,” Terry recalled telling him. “I don’t love this. It’s causing me to have panic attacks.”

He took a leave of absence from the Mavericks. He ignored texts from his mother. He had played in 11 N.B.A. games.

In recent years, the N.B.A. and its players’ union have beefed up their mental health programs. Each team must employ at least one full-time licensed mental health professional. The players’ union has a national network of professionals whom players can contact anonymously.

Terry said Dallas’s psychiatrist had prescribed two anti-anxiety medications. Sometimes they helped. Sometimes they made him nauseous. The psychiatrist lost his trust, Terry said, when he asked Terry when he could tell the team he would be ready to practice again. The Mavericks declined to comment, saying it was Terry’s story to tell.

At his agent’s suggestion, Terry also tried guided psychedelic therapy, and found some comfort in it. He still engages in it today.

Grise, Terry’s mother, wanted to rush to Dallas when Tyrell took his leave. A friend talked her out of it, she said, suggesting that he might see it as an intrusion.

When she visited a few months later, he said something that helped her understand how distressed he was: “If I was a garbage man and I told you I wasn’t happy with my job, what would you tell me? What’s the difference other than money?”

Before that, Grise had thought Terry just needed to give himself more time to feel comfortable in the N.B.A.

By that fall, Terry’s anxiety was crushing him and he didn’t think anyone, not even his mother, really understood. Training camp for the new season was beginning, but Terry couldn’t face it. One morning, he called his agent and told him he was done. The Mavericks agreed to release him.

He gave the game another try a few months later, signing a contract under which he split his time between the Memphis Grizzlies and their developmental team in the G League, the Hustle. He said he had sought camaraderie on the Hustle but had found that most of his teammates prioritized earning a shot in the N.B.A. Little things, he found, created tension between him and his teammates. For example, he sat in first class on flights because of a stipulation in his contract, while older, taller players passed him on their way to coach.

Memphis cut him after the season, and he headed to play in Germany in the fall, clinging to the possibility that a new setting would unlock something inside him.

‘My Dad Didn’t Even Come Around’

On a crisp, sunny day in early April, four months after he had left his basketball life behind, Tyrell Terry drove the 25 minutes from his new apartment to Stanford’s campus in Palo Alto, Calif.

He parked near Maples Pavilion, the intimate arena where thousands had once cheered him on. He strapped on a Stanford backpack over a long-sleeved plaid shirt and climbed on his bicycle. He navigated to his first classes in three years.

Maybe, he has thought, his basketball journey could have turned out differently.

Tyrell Terry’s father was also a basketball savant. Tyron Terry was named North Dakota’s Mr. Basketball in 2000, the same year Tyrell was born.

After Tyrell’s parents split up, Tyron started a new family in North Dakota, so father and son did not spend a lot of time together. Still, Tyron said he had made Tyrell a priority, driving in snowstorms to see him, taking him to Disneyland and a Lakers playoff game against the Phoenix Suns. Tyrell stayed with him in North Dakota one summer.

Basketball was a source of both connection and estrangement for them.

Tyrell recalled proudly showing his father his first YouTube mixtape, only for Tyron to reply that mixtapes did not make decent players. Tyron said his son had enjoyed discussing the ins and outs of basketball but had favored lighthearted shooting over intensive training. He said Tyrell had been coddled in childhood.

“When things got hard, he never had the chance to just grow from it,” Tyron said.

Tyrell said his father had bullied him in a one-on-one game to make a point, leaving him in tears.

“I get the tough love,” Tyrell said. “But I was just looking for a time in my childhood where my dad was just proud of me. I never really got that.”

Minor squabbles became major disputes, and at some point when Tyrell was in high school, he and his father stopped talking, and they haven’t spoken since.

Once, Tyrell offered his father a ticket to a Stanford game after Tyron’s wife, Heidi, had reached out. But they did not speak to each other there, and Tyron wasn’t at his son’s draft night party.

Nor did he call when Tyrell took leave in Dallas, signed with Memphis or left for Germany.

“I believe this: I looked up to my dad so much that I think if my dad was in my life while I was in the N.B.A., he could’ve told me the right things to get over that hump,” Tyrell said.

“I had made it,” he continued. “I had done everything my parents wanted me to. I got into Stanford. I made it to the N.B.A., and I was wealthy, and I didn’t feel fulfilled. I knew at that point that I just did it, for the most part, for them. And then my dad didn’t even come around.”

Tyron said he had read Tyrell’s retirement post with regret. He felt he could have made a difference. He said he had always thought they could repair their relationship once Tyrell had children and “understood everything that I did for him.”

Choosing His Majors

Terry is still dealing with the response to his sudden retirement. He had spoken to some well-wishers, but others, including an old high school coach, were still waiting for him to text back.

“I didn’t have the courage to have a conversation with certain people,” Terry said. “Now that I’m doing better, it’s hard to get those type of people to understand that it wasn’t personal, but I was just in such a bad spot that, honestly, being alone is my comfortability.”

Recently, Terry said, he answered “invasive” questions from N.B.A. doctors about his mental health as part of the process through which the Mavericks will have his $1.8 million salary from the 2022-23 season removed from their books. He felt obligated to participate, since Dallas had let him keep the money from his contract when he asked to be released.

“Whether it was all my fault or not, or whether it was all contributed to mental health or not, I would say I failed in the N.B.A.,” Terry said. “I’m OK with that.”

He added, “I had the talent, but it’s not what drives me, not what fulfills me.”

The Stanford campus feels familiar beyond some new construction. Many of his freshman-year classmates are graduating and starting their lives. Terry has already lived at least one version of his. He enrolled in four classes and plans to major in science, technology and society.

He locked his bike just outside the main quad and walked into a cavernous classroom, blending in among dozens of students, settling in, settling back.