Missing posts?
If not in the logs then it's self deletion.
If user deletion is turned off by BO then database might act up.
Or perhaps the posts aren't missing, and you guys are mistaken (perhaps those posts you are looking for are in a different thread).
Maybe looking for post numbers which are missing could help, but if a thread got deleted then obviously there will be missing post numbers.
In any way we can't restore posts, we aren't archive anything. Database "restore" is just fixing threads that falsely display 404 when opened.