Threads often get moved to the appropriate forum; there are so many forums here that even long-time regulars sometimes aren't sure which forum to post in -- but we don't normally delete posts, especially without explanation. What forums were these posts in? Are you sure they're gone? (That probably sounds like a stoopid question, but we often get complaints about missing posts that turn out to be still there -- people don't realize they posted it in the wrong forum by mistake, or they forget what title they gave it, or sometimes it's only that it isn't on the first page of the forum any more.)
One more question -- were they recent posts? We deleted the old posts from some forums recently, but they were months old at least.