I had this problem with conversation where all my msg went missing. Yesterday my battery ran flat. I recharged and when I open Conversation, no conversation listed. But when I sms to a contact, all the history text returned. After a while of receiving texts, when I select to delete one msg, all other msg gone.
Another problem, this happened first, any IM msg, no history is stored. Once I close the IM, all history cleared and start fresh history when the same contact start a new IM and IM are not stored in Conversation as well.
I had my internal 32G memory corrupted. This doesnt bother much as I still had 8G external. But conversation problem does as I lost track who I had been chatting on IM!
Hope someone have similar problem and had a workaround to this issue.

Thanks.