Check your windows event viewer, you might have had a display driver crash. usualy nvxxxx.dll for Nvidia cards. It happened to me in games and also in windows

I have had the same issue intermittently when using either a DVI 1280x1024 monitor or a 27 " HDMI BenQ XL2720T.

I did nothing to fix it, it stopped on its own. I changed drivers with no effect previously apart from making things worse (new problems)