Either go to a working Windows 10 Machine or download files from here

Take Ownership of C:\programdata\Microsoft\Windows\AppRepository ( and Subfolders ) 

Then Open C:\programdata\Microsoft\Windows\AppRepository ( Click Continue to add security ) 

Then Open C:\programdata\Microsoft\Windows\AppRepository\Packages ( Click Continue to add security ) 

Copy the correct ActivationStore.dat from the downloaded Zip or a working PC to the folders in here ( Make sure you copy to each folder ) 

C:\programdata\Microsoft\Windows\AppRepository\Packages\Microsoft.Windows.ShellExperienceHost*
C:\programdata\Microsoft\Windows\AppRepository\Packages\Microsoft.Windows.StartMenuExperienceHost*
C:\programdata\Microsoft\Windows\AppRepository\Packages\Microsoft.Windows.Cortana*
C:\programdata\Microsoft\Windows\AppRepository\Packages\Microsoft.AAD.BrokerPlugin*