Sounds like anything from malware to a corrupt profile.
Start Windows in safe mode. The instructions are here. There are several ways to get there but from the login screen, based upon the docs, hold Shift while clicking the Restart button under Power.
When Windows restarts select the Troubleshoot option, Advanced Options, Startup Settings. Then click Restart and on the restart menu select Safe Mode. Once in safe mode see if the desktop icons show up and things behave correctly. If so things might be working again so you could restart and log in normally.
Otherwise create a new user profile. Then restart Windows and log in using the new profile. If things are still corrupt it isn't your profile. It could be malware, a corrupt OS install (although I cannot imagine what) or perhaps a keyboard/mouse failure that is causing inputs to be sent to Windows. At this point, assuming you've already scanned for malware, your best option might be to repair Windows.
If creating a new user profile worked then copy your desktop, documents, etc from the old profile folder to the new one before you remove the old profile.