Press CTRL + Z to undo things like renaming a file in Explorer.
Personally, I felt sometimes the need of getting back to the original folder name when It was erased by mistake (before ending it). I didn't know how to do it. Well, now, I know.
It seems that this functionality works for other things than renaming. I use it sometimes to go back in the "Solitair" game. Anyone has any idea to use it in other domains?