can't save my game

tayatfairley​  Does it help to click alt-F4?  That should give you the prompt to save, and clicking Return/Enter may allow you to confirm.

If this problem happens again, see whether it helps to play in windowed mode next time.  If you can't change the setting in-game, open Options.ini, in Documents > Electronic Arts > The Sims 4, search for fullscreen , and set it to 0 (zero).  This applies to the fullscreen setting, not anything else with that in the name.