Wow that's a big question! It depends on the problem...
Th bottomline is that it sounds like the shape of the frame (&/or door) has changed since you gutted it. I assume your floor is out too, if so what is keeping the shape intact? Are the channels that the ribs are supported on attached to or supported by anything? If not the whole shell can "fltten" or sag out of shape. Any pictures you have could help us understand what you are up against ~
Regardless, if you can return the shape back to what it was prior to gutting and removing the floor when you reinstall it, it should be okay...but if your door's hinges are sprung or your door's shape is modified or flattened, it could be a whole different fix.
Any additional info or clues will help...we just replaced our floor (shell on) and once it was all put back together it's been fine - but our door closed fine even with the floor out because it was supported the entire time. The key is to knowing exactly
how it was before
the gutting - so you can
put it back together. Hope you took lots of pictures & measurements rather than just relying on your memory, trial & error ~