The usual cause of disappearance of desktop items is a corrupted account, which makes Windows log in into a temporary account that doesn't have your desktop items, but it's own empty desktop.
Log in into your spare (admin) account to see if that works correctly. If you forgot to make such an account, boot into recovery mode (you might need a Windows 10 install DVD or stick, which are free to make, if you forgot to make a recovery drive) and make one with the net command in command mode. Then login into that, make a few icons, log out and login again. Are they still there?
When ready, you'll agree that having a spare admin account and making a recovery drive are recommended practices for every Windows user.
But, of course, something else may be wrong with you. A common reason for slowing down is a bad hard disk, and if it's bad where it stores your desktop or where Explorer is located, well, then everything unexpected can happen.
Then a new hard disk is the usual solution.
Or you have some nasty malware messing up things. Then the best solution is to go back to factory conditions or do a clean reinstall of Windows yourself.
A more detailed investigation might tell more. If you feel you can't do that yourself, find a repair shop.
When I booted this morning none of the desktop icons showed. I checked all settings and all seems fine. In addition in the Desktop folder all the stuff is there. I even booted in Safe Mode and they didn't show.
In addition, right-click doesn't work on the desktop and the machine seems considerably slower.