Welcome to Last Moon!
And to answer your questions; no you can't change the hotkeys, and for the second question. You'll want to PM an admin or game owner about it, that item is not broken, so it should not have disappeared. Did you check in your stash to see if you accidentally stashed it? (press I and then click "Stash").
Thank you both for replying :)
I did already check my stash and it isn't in there. Do you have any names of admins I could contact? I just don't know anyone yet, that's all. Thank you for your help ^_^
The two admins are Dutchval and Husky275, Dutchval tends to deal more with in-game issues like what you are having.