I was working with various layers in photoshop (cc 2018) on my Mac (Sierra 10.12.6). I had made several major changes to my project including rotating my canvas, placing a new image, making edits in camera raw filter, using the blur filter etc. The last step I made was to duplicate the layer I was working on. As soon as I did that, it reverted all of my changes back to the last time I duplicated a layer. About 10 minutes worth of work was gone. It wasn't in the history either. It's as if I had never done any of that work.
10 minutes isn't a very long time and luckily I save often and won't have to redo a ton of work. But it was concerning and I was just curious if anyone else had encountered this problem.
My husband is convinced that I must have 'hit a button' that caused this to happen. I did. "Command J"! It just doesn't make any sense.
The default shortcut for File > Revert is F12. Are you sure you haven't accidentally hit it?