This is not a common problem, but for future reference, if you can not use a teleporter stone to get back into the normal play area, there are a couple other fixes for the character getting through a wall. This situation can also be cause by using Flash Attack to jump to an otherwise inaccessible location (into the lower level of the sewers or onto the mountains in the Dark Forest), without leaving an enemy behind to be able to get back out.

FIX for the Missing Catacombs Portal

Teleporting Anywhere, via hex editor