system
6
Try this:
http://answers.microsoft.com/en-us/windows/forum/windows_10-windows_install/73115-windows-10-start-menu-does-not-work-what-do/6a8fc2a0-fb92-4961-b11b-2443977b2c73
Method 2 worked for me. No need to reinstall windows 10 or even restart your computer!