If someone deletes a comment or wall post, can it be un-deleted on Facebook?
Most likely not, but theoretically you could try getting the feed for your own status updates and see your deleted posts there.
This comment gives the details on how to get the feed. Basically, you need to get a friend to create a friend list, then have them give you the friend list ID, then you have to add "flid=" to the end of the URL. The comment will clarify things.