Curry ~
You should have also received an email alerting you about the posted message. If you didn't delete the email, you may be able to find it there. If you know approx. when you received the post, that should help.
I'm not sure if there is a list for all your messages on WikiTree. Perhaps someone else here will know of away and answer. .
You can get a list of all your emails from WikiTree from your email account (if not deleted). I believe most if not all types of messages from WikiTree will go to your email box.
Hope this helps!