When you noticed one of your posts has disapeared from a thread, and you have reason to believe it has been deleted from a thread do not, and I repeat do not, repost it. If it has been deleted by a mod there is a reason. Give it a few minutes then check your inbox, or look for annoucements from a mod to see what you did wrong. If neither arrives contact a moderator from that part of the forum (you can find who that is by clicking on the "Forum Leaders" button at the bottom of the list of forums) and ask him what is up. We mods are human, except H&G who is a googlebot, and we make mistakes and may not inform you why the post is deleted. The moderator of that forum can find out easily for you.
So again, do not repost deleted posts. Doing so may result in a warning or even a suspension. If you do it accidently inform a mod and we can look at it and judge if it was an accident.