If you stack with this annoying bug of a non working start button, you can try the following workout.
Using task manager kill (end task) Windows explorer service.
Click on 'File' menu then 'Run new task' and browse to
You will have several warnings that some file cannot be deleted. In all these cases click 'Skip'.
Click on File menu then 'Run new task' and type
Right click on start icon and choose
Shutdown or sign out Restart
After reboot, your system hopefully will have a working Start button