A door that comes off its tracks looks worse than it usually is, which is small comfort when it is hanging crooked in the opening. The cause is usually one of three things: something was in the door's path on the way down, the door got bumped by a vehicle, or a roller or cable failed and let the door twist out of the track.
What you are looking at
One side of the door visibly lower or tilted, rollers out of the track on one side
The door stopped mid-travel at an angle, stuck because it cannot move straight
A gap between the rollers and the track, or rollers lying on the floor
Cable off the drum on one side, which is how most doors get crooked in the first place
Do not force it
A door off its tracks is a door that can drop. Pushing on the opener, tugging the door, or yanking the emergency release on an unbalanced door are all ways to turn a realignment into a fallen door or a hurt person. Leave it where it is and keep people clear of it until the tech gets there.
What the repair actually involves
Get the door stable, work the rollers back into the track, square the door, and figure out why it came off. That last part is what separates a fix from a repeat visit. If the track is bent, a cable frayed, or a roller failed, resetting the door without addressing the cause just resets the calendar until it happens again.
When it is not just the track
If the door hit something hard enough to come out of the tracks, panels can be creased, hinges bent, and the track itself deformed. A real reset includes checking all of it, and an honest tech will say when the same money goes further toward a panel or door replacement instead of straightening bent hardware.
