Zac Efron - 17 Again

In 1989, 17 year-old Mike O'Donnell learns from his girlfriend Scarlett that she is pregnant during the final quarter of his high school-championship basketball game. However, just moments before scoring the winning basket, Mike abandons the game, and a possible college basketball scholarship, to chase Scarlett down the hall and propose to her.

Twenty years later, Mike finds his life stalled. Scarlett has separated from him due to his regrets about abandoning college, forcing him to move in with his geeky and wealthy best friend since high school, Ned Gold; he quits his job and his high school-age children Maggie and Alex want nothing to do with him. Later, while visiting his high School to reminisce, an encounter with a mysterious janitor transforms Mike into his 17 year-old self.

Given the chance to re-live his youth, Mike enrolls in high school posing as Mark Gold, Ned's son, and plans to go to college with a basketball scholarship. As he befriends his children, however, Mike comes to believe that his mission is to help them. Mike comforts Maggie when her boyfriend Stan, the captain of the basketball team, dumps her. With his help, Alex overcomes Stan's bullying to obtain a place with Mike on the basketball team and the girlfriend he desires. Through their children Mike spends time with Scarlett, who is attracted to his remarkable resemblance to her husband in high school. Mike has difficulty resisting his desire for her despite the relationship's apparent inappropriateness. At the same time, he resists Maggie's growing infatuation with him by telling her that he loves another. Meanwhile, Ned courts Jane Masterson, the high school principal who shares a mutual interest in The Lord of the Rings.

Mike soon realizes that Scarlett is the "best decision" he had ever made and tries to re-unite with her and unsuccessfully explains to her that he is actually Mike, her husband. During a high school basketball game, Mike reveals himself to Scarlett. As Scarlet once again runs away down the hall, Mike decides to chase her down once more, but not before handing the ball off to his son so he can have the scholarship. Mike is then transformed back into his 37 year-old self and is reunited with Scarlet. Meanwhile, Ned and Jane begin dating and Mike is hired as High School's new basketball coach.