Board Thread:Support Requests - Getting Started/@comment-24596312-20180712170200/@comment-9605025-20180712173841

Now that I have tested it, I see what you mean. However, you should be able to go to the thread's history. There, you should see a record of you removing the post with a link in parenthesis to restore it.

That is, assuming you removed rather than deleted the post. If you actually deleted the post, you will first need to restore the post's page. To do that, go to "Special:Log/delete" and find the entry for the post in question. At the end of the entry, there should be a link to "view/restore" the page.