I'm playing through the game and I didn't make any saves before I started the quest to clear out the Keep. When I finished, I found that I had missed the Flail Head [Cold] and thus couldn't complete the Flail of Ages. When I went to the location in the keep where the cold head was supposed to be located, it was mysteriously absent.
Is it possible to collect loot that I missed after I've completed the quest to clear out the keep? Or am I hosed?
P.S. My main is a Fighter class, so I was offered the opportunity to take ownership of the keep -- which I accepted. If that matters.