Uh oh, so you're working on some super l33t code or other stuff that is super important and Linux Mint's MATE or Cinnamon window manager freezes. This means maybe you can move your mouse but you can't click anything, you can't Alt + Tab to another program but everything appears to be working other than that.
The first thing you would do is Ctrl + Alt + F1 (or whatever virtual terminal you want) and get into the Linux bash prompt (the black screen where things really happen :))
Sometimes people will try killing the mint-panel or filemanager as this can sometimes be the cause of it.
So you've tried the basics, tried to restart the mint-panel or caja filemanager but it doesn't work?
You're probably close to rebooting, or booting your PC out of the window at this point. But wait there is Ctrl + Alt + Backspace (but don't do this). You would lose all of your current open windows
Linux MINT Mate How To Restart the GUI without losing open windows
DISPLAY=:0 marco --replace&
Linux MINT Cinnamon How To Restart the GUI without losing open windows
DISPLAY=:0 cinnamon --replace&
Ubuntu Linux How To Restart the GUI without losing open windows
DISPLAY=:0 unity --replace&
The key thing is to use the --replace because that means to replace the existing session so the windows and open programs you have are preserved.
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