If you happen to screw windows 8/10 modern apps when cleaning AppLocal blindly, you can rebuild the config/install of Microsoft store and core apps so :
- Run Powershell as admin
- Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register « $($_.InstallLocation)AppXManifest.xml »}
- Wait and pray
Get more tips from : http://www.urtech.ca/2015/05/solved-windows-10-start-menu-and-modern-apps-do-not-function/ or http://www.thewindowsclub.com/start-menu-does-not-open-windows-10