Yup, I cant find that [Revert] button. 
I faced that same exact thing but on a different forum.
No idea how to solve.
I believe the message becomes un-revertible after a set period of time, how soon did you try to revert the message deletion after you sent it?
Pretty quickly, i think. Definitely below 30 mins.
I also tried another one, tried it immediately but the button just wasnt there.