Alright type in search box "mdsched.exe" it will run test for your memory if anything bad happened but first of all I suggest you to run in cmd.exe with administrator priviliges "sfc /scannow" it will check if something was corrupted in windows after updates and such after that run "mdsched.exe" also If you run "sfc /scannow" It might enable again cortana even I don't know whats your windows so keep an eye on it