Clipboard stopped working
Solution 1:
Found a solution here
Run the following: cmd /c "echo off | clip"
You can even make it into a desktop shortcut if the problem keeps happening.
Solution 2:
For me the problem was happening only when there was a RDP session open to another machine. After closing RDC, clipboard started working again.
Solution 3:
If this is over Remote Desktop (RDP) then ensure that rdpclip.exe is running on the remote machine. You can start it using Win+R and then rdpclip
Solution 4:
There's probably an app that's "locked" the clipboard. Try and work out what app has done that and close it.
In my case it was a hung Greenshot.