If the door is off-track but the opener is disconnected and the door is sitting still, it's reasonably safe to look at. Pull the emergency release, check whether the issue is a bent track, a jumped roller, or a loose bracket. Tightening a lag bolt on a bracket that's backed out half an inch is a fifteen-minute fix most people can do.
What isn't a DIY job is anything involving the torsion spring or trying to force a door back into its tracks while it's under spring tension. A door that's jumped track on one side with the spring still wound is storing enough force to break fingers or worse if it lets go while you're wrestling it. If straightening the track means loosening the spring first, that's where this stops being a weekend project.