Do not try to fix it yourself, as it may make things worse. Find where the wheels have leapt the track, apply a set of locking pliers beneath the door on one of the tracks to act as a quit. Pull the beyond the track open with an additional pair http://andersonoiaqf.blogolize.com/The-Main-Principles-Of-Garage-Door-Off-Track-Repair-Porter-Ranch-39555007