Oop- I just found a bug!
If you go to a door, click "open door" without having a key in your inventory and then press nevermind leave - the character walks forward into the locked room (which in my case was a chest room), it will not give you the chest, instead it will lock you inside that one square of a room and say "pathway blocked" when you try and klick outside it.... And since you don't have a key, you're now stuck forever
:) unless you want to go back to a save - which in my case, means that I had to start over from the beginning, because apparently it hadn't saved since then...