Brutal Legend

Eddie Riggs (voiced by Jack Black), an average roadie for an average Second Wave of American Tween Melodic Rap Metalcore band is transported to the Land of Metal, where he must teach its people the ways of true metal to free them from enslavement by the demons of the Tainted Coil. For literally all intents and purposes, it's a story that is neoclassical metal wish fulfillment, backed up by one hell of a soundtrack that encompasses pretty much all forms of metal.

Example of:
Trapped in Another World