icons disappeared from my Mac desktop

Did you turn on iCloud Drive perchance?

Safe Boot, (holding Shift key down at startup), does the problem occur in Safe Mode? Could take 10 minutes.

Safe mode attempts to repair Disks & clears lots of caches & loads safe Drivers, & prevents loading of 3rd party extensions, so if Safe Mode works try again in regular boot.

Same issue happens to me on occasion. I simply restart it and they all come back.