Ugh! Redo has worked for me. Have you tried both clicking in history and redo menu item? But no other suggestions from me sorry. Hopefully someone from Adobe is listening and has a better idea.
I would make a copy and then try refreshing. I don't know if that will work, because you now have the "newer" version.
But I had something similar and when I closed out and rebooted the full history came up. Good luck. Not sure if mine was the same. Although I'm sure the pain and panic was. LOL!
Sorry to hear about this. It's a downside of allowing you to go so far back in time -- if you make a change while you're back there it clears out all the redos. Not that it helps you right now, but our next release will allow you to recover from this situation easily.
But all is not necessarily lost. If you send me your project (zip up the whole folder and send me a private dropbox link or equivalent) we'll try to recover it. The odds are pretty good because even when redos are unreachable, they are not deleted. Note that Save Project As... completely clears history, so we'll need the original project, not a Saved-As version.