The problem is, I was fooling around in single player and I did an awesome move, but then I couldn't remember how to do it.

Here it is
what a rip off .rpl


Could anyone help me figure it out?

Hit E to edit the replay and see what you did. Not much else you can do to recover it.

Also, just a tip, as you are creating replays, press "F" to save it anytime you make a drastic edit, that way you won't accidentally forget and lose your replay.