I don't remember much about the but the basic plot was that this guy travels back in the to the body of his younger self but still has all his memory. In one episode he does his old/future job neglecting his best friend. When he gets caught he gives his father the money and tell him to invest in Microsoft but the father buys a jacuzzi instead. At the end of the episode he and his best friend are standing in line to see star wars and he gives spoilers for the movies and gets knock out. In another episode he sings "Time of your life" by green day for star search but decides to give them credit by the end of the episode.

Do Over (2002)

From Wikipedia:
"Do Over" is an American comedy-drama/fantasy series created by Kenny Schwartz and Rick Wiener about a man who gets a chance to relive his childhood. The series, which was originally broadcast on The WB in 2002, stars Penn Badgley.

The series begins showing an adult Joel Larsen as a single, depressed salesman disappointed with how his life has turned out. Joel missed a lot of opportunities, his once-popular sister is now a drug-addict, his idealistic best friend sold out, and his mother ran off and left his father an unhealthy, bitter man. However, a freak accident sends Joel back to 1981 as a 14-year old. He wakes up in his teenage body, but with all his adult memories from 2002 intact. He eventually accepts this new reality, although he tells no one except his best friend. Blessed with adult wisdom, though hampered by adolescent urges, Joel sets out to right the wrongs that will befall him and his family.
Joel is forced to readjust to the culture of the early 1980s, to junior high, and the tribulations of adolescence. He is forced to relive certain moments of his life, but is always determined to improve the outcome. A running gag in the show is Joel's creative mother coming up with a "new" invention (fanny pack, Lunchables, post-its, etc.) which is usually ridiculed by the father, who instead wants to invest in items such as asbestos tile, Betamax cassettes, or electric typewriters. Some episodes show Joel using his knowledge of the future for personal gain: investing in Intel stock, palming off 1990s song hits as his own, befriending a future billionaire, etc. However, the situations never work out according to plan and Joel usually ends up realizing he needs to use this opportunity to help himself, his family and friends take different paths. The final episode of the series shows Joel convincing his father to invest in one of his mother's inventions, which to Joel's surprise is the one invention that doesn't exist in the future. It ends with Joel and his family toasting the future.

Do Over - Wikipedia, the free encyclopedia