Hello deadlineboy
first a hint, cheats can permanently damage the game, at least in the wrong place or at the wrong time!
We usually can't repair such bugs.
If any game problems occur, better always ask us before using a console!
About your score:
You probably shot the key and other items in the last fight.
If you turn around now and go back downstairs, you will see a railing through the door you cracked.
(With a stone table right behind it in the room with all the undead).
Now if you stand so that the big round table is directly behind your back, there is said railing in front of you,
next to the stone table on the bottom righthand side of the floor is a sheet of paper and under it just the key you're looking for.
(yes, a pretty lousy coincidence).
Take this key and everything goes on as planned^.