Happened to me tonight on Windows 10 -- also happened a couple of months ago. My laptop is old, so who knows?
In any case, easy fix.
1. Open up the Task Manager (CTRL ALT DEL).
2. Make sure View in the menu bar doesn't have anything checked. Sort by the name column. Hit CTRL END to go the bottom.
3. Scroll up a few to the Windows Explorer process.
4. Right click and select Restart.
That's it! Gotta get my new laptop set up -- had it for a few months already.