Right click on Start button> Run
Type in: sfc /scannow
Windows will repair itself. I had to do this when several problems came when I did an upgrade. One item was not able to left click on the Start button.
Most were fixed but it seemed sluggish so I did a format during the install and all was well. I had backed up my files prior to the upgrade.
Ok thanks. I’ll try that if/when I upgrade again. If it’s like before though I’m not sure even this would work because last time I couldn’t left click on the Start menu. But maybe I could right click.