A snapped lift cable is not a project to fix with the garage door up and the spring still loaded. The cable runs under tension from the bottom bracket up to the drum on the torsion shaft, and when it lets go, the door can drop or tip hard to one side with no warning. If your door is sitting crooked, won't stay up, or a cable has jumped off the drum, the safe move is to leave the opener unplugged, block the door from closing the rest of the way if it's stuck up, and call it in. We're straightforward about what this job needs: proper winding bars, clamps, and a feel for spring tension that most homeowners never have reason to develop. Replacing a cable yourself usually means also disturbing the spring system, and that's where most garage injuries happen. This isn't a job we'd want a neighbor doing either, honestly - it's cheap to get wrong and expensive to get wrong twice.