I am using a tool stardock which by the way does not work automatically--the stardock tool allows shortcuts to open saved applications or files. The Task Manager WindowsExplorer right-click restart does bring the Start key for a moment, then it disappears. I tried the commands you suggest, no issues were found for SFC /SCANNOW.
I tried the DISM commands you provided (they took some time but it finished 100%) but the start key does not return after a reboot.
I have tried to Contact Microsoft Help but they have not responded yet (help.microsoft.com)
Ralph ******@gmail.com