Board Thread:Support Requests - Community Management/@comment-4904721-20140806023236/@comment-5558012-20140806024336

Forum: Go to original post -> Click More -> History -> You see something like "User1 removed User2's reply #23" -> Go back to original thread -> In the URL you see Thread:717789, add the number to it, ie Thread:717789#23 -> Enter and you can see the post without restoring it. (I'm pretty sure there is a script to make this easier.)

Message Wall: WallGreetingButton is the way to go.

Edit: Sorry, I misread your question. The above assumes you know where they deleted posts (or you can just look for them).