Rarely do things get "deleted." There are a hand full of edits a week per few thousand posts, and some hot, reported, controversial threads do get moved temporarily for discussion, but few disappear forever, unless of course it is completely against the rules we try to keep for a family friendly site.
Chances are, if you can't find it, it rolled off the first few pages of recent posts! Often if you remember key words, you can use the search function and find it again.