Windows

This is a Software issue that was brought about by User Misuse. There is a limit to what can be dumped onto the desktop in any OS and when you exceed this the system becomes unstable.

So if you are a Professional IT Person wipe the entire system and recover from your Backup that will save you lots of time and effort.

However if you are not a Professional IT person you'll need to open the desktop and delete each and every Icon that you have put there. It's going to take some time and effort but as you got it there it's only fair that you remove it and don't dump the job onto some poor unsuspecting fool who is not at fault.

If the system is unresponsive and is a Windows OS you can always boot into Safe Mode which loads a Minimal Set of Drivers and delete things that way but as you didn't list the OS I can only give you general directions on how to get into Safe Mode. When the computer POST's you'll see a message that you can press any key to boot from something and then you'll see another message on a White on Black Screen at that point press and hold down the F8 Key till you get a White on Black Screen giving you various option on how to boot Windows you want to use the Arrow Keys to highlight Safe Mode and then press ENTER.

When the desktop opens navigate to the Desktop Folder and start deleting the junk you dumped to the Desktop.

I'll not even attempt to suggest ways to deal with a Linus or BSD OS as they vary so much that there is not enough room here to even begin to list the directions necessary.