Amnesia The Dark Descent Help?

I've been playing Amnesia and in the machine room where you have to use the gears to restart the elevator, my game glitched and the final gear I needed disappeared. It did not end up back at the place that I had gotten it from and after several attempts at running around to find it and even leaving the room I have not been able to figure out what to do. I really don't want to restart the game because that would be a pain the ***...so is there anything I can do?