From Rocklopedia Fakebandica
Pop Rocks (2004). Turns out normal dad Jerry (Gary Cole) used to be Dagger, the lead singer for this '80s one-hit wonder hair metal band.
He gets hit up by the other members to reunite for a high-paying reunion gig. Jerry only does it for the money to put his kids through college and tries to keep his participation a secret from his family. The lead guitarist is Izzy (David Jensen).