If you can not (or do not want to) revert to an earlier game, there are work-arounds. If possible, re-doing part of the game would probably be easier.

to get past sealed doors/hatches
FIX for the Missing Catacombs Portal
or
Teleporting Anywhere, via hex editor

to replace the set of teleporter stones (put the one you have left in a chest, or something)
Lost Items - guide and directory of inventory files