rat - Saz gave you excellent advice so you can skip the part about the snake idol and the Book of the Servant.
Are you saving your game often and to different save slots?? It is a really good idea to save before you enter a dungeon in one slot and part way through the dungeon in another slot. That way, if you miss something, you don't have too far to back track.
The other alternative is to use revert game (NOT reset adventures) which takes you back to the last time you visited a town. Multiple saves is a much better strategy!
Wyv