Windows 7 - Windows explorer stoped working...

I just restarted my PC and it sais that windows explorer is not responding....
What to do?

Turn off your antivirus and boot.

Try to boot in safe mode

If you can run an antivirus scan. Download, if you can, malwarebytes and do a scan.

Did you do a clean install or upgrade?

If you have previous system restore points to choose from, try to restore to a point previous to the last program/setting you installed/changed.

I've had issues with explorer caused by third party themes, especially when forced to replace the stock explorer.exe. If you find that explorer.exe isn't responding, you can usually get it to reboot itself if you open the task manager and close the program and then start it up again via task manager.

Ctrl-Alt-Delete
Task Manager
Processes Tab
Highlight "Explorer.exe"
End Process
File > New Task (Run...)
Explorer.exe

This is only a temporary workaround until you find the cause of your problems.