Well, ignoring for a moment the lack of evidence that would suggest that time travel is anything but incoherent sci-fi mumbo jumbo, the sequence of events is this;


1) You make the post

2) Someone develops a machine that can throw all the events of the Universe into reverse order, which in itself breaks most laws of nature.

3) They do this.

4) You affect a change that prevents you from making this post under new-time.





1 remains a true thing, however. While you can affect changes that make it seem as if it never happened, and the evidence of it's occuring is not eternal, it will be eternally true that it happened. The truth is immutable.