17 Again (2009)

Mike O'Donnell (played by Matthew Perry) is reflecting on his life, feeling unhappy and unsatisfied with the choices he made. In 1989, Mike was a popular and talented high school basketball player with a bright future ahead. However, when his girlfriend Scarlett (Melora Hardin) tells him she is pregnant, Mike decides to give up his scholarship and marry her, putting his dreams on hold.

Fast forward seventeen years, Mike's life has taken a downward turn. He is middle-aged, frustrated in his marriage, and estranged from his children. His wife, Scarlett (Leslie Mann), asks him for a divorce. Feeling lost, Mike goes to visit his high school for a reunion party and encounters a mysterious janitor (Brian Doyle-Murray) who magically transforms him into his seventeen-year-old self (played by Zac Efron).

Now masquerading as the young Mark Gold, Mike enrolls in high school to relive his glory days and set things right. He meets his nerdy and outcast son, Alex (Sterling Knight), who believes Mark is a new student and befriends him. Mike also befriends his daughter, Maggie (Michelle Trachtenberg), who initially dislikes him but eventually opens up.

While attending high school, Mike discovers that his kids are going through difficult times. Alex is relentlessly bullied by a jock named Stan (Hunter Parrish), while Maggie is dating the arrogant and selfish bully, Stan. Realizing that his role goes beyond reliving his youth, Mike decides to use this opportunity to help his kids and guide them to a better path.

With the help of his best friend Ned (Thomas Lennon), who is the only one who realises that Mark is actually Mike, Mike starts to make positive changes in his kids' lives. He helps Alex gain confidence, teaching him basketball and guiding him to stand up against the bullies. Mike also coaches the school's basketball team, turning them from underdogs to champions.

Meanwhile, Mike's attraction to Maggie grows, but he must remind himself that he is actually her father. As the school year progresses, Maggie begins to see Mark as a mentor and turns to him for advice. Mike tries to subtly steer her away from Stan and towards her academic dreams, showing her that she deserves better.

As Mike embraces his role as a father, he slowly starts to realise that his own selfishness and choices caused his family to fall apart. He witnesses how his wife, Scarlett, is in an unhappy relationship with Stan, who is also cheating on her. Mike becomes determined to repair his relationship with Scarlett and reunite their family.

During the championship basketball game, Mike's secret is exposed when Ned accidentally reveals his true identity on live television. Despite the initial shock, Mike's family comes together to support him. Maggie forgives him for keeping the truth from her, and they all work together to reconcile Scarlett and Mike.

In the end, Mike learns that his family is more important than trying to relive his glory days. Scarlett decides not to divorce him, and they agree to work on rebuilding their relationship. Mike also accepts that his dreams of being a basketball star will never be realised, but he finds contentment in being a loving father and husband.

The movie concludes with Mike, now back in his middle-aged body, making amends with his children and promising to be a better father. The O'Donnell family celebrates their new beginning as they attend Alex's basketball game, where Mike realises the true value of family love and support.