I purchased the Shivering Isles expansion a while back, and started the main quest. I decided to go back to Cyradiil and do other stuff before really getting into Shivering Isles. 100 hours later I went back to Shivering Isles to continue what I already started. I had to go to Xedilian and activate the Resonator of Judgment with the Attenuator of Judgment. The only problem is apparently I don't have the Attenuator of Judgment anymore! Is it possible that quest items from Shivering Isles disappear when you go back to Cyradiil??? Also, this doesn't really matter, but I don't have that book that you get from Sheogorath either...

Not sure what to do other than start over. I'd rather not do that. Please Help!!! Any ideas?!