Running Win 10, 64 bit. Just upgraded to the latest big deal. Anyway, b4 upgrade all hard drive letters displayed correctly in the listing @ the left side of File Explorer (a vertical column starting with "Quick access" and after several more entries has "This PC" and a listing of all the hard drives. This is now missing the boot drive (C on a physical disk (SSD) and two additional logical drives (on another physical disk). If I click on "This PC" all drive letters (including the missing trio) show in the "Devices & drives" on the right side of the box. Clicking on them makes their contents visible. In addition, the Control Panel...Storage...Disk Management module shows all drives as "healthy". Granted, this is a minor irritation but how do I restore the hidden drives to the "This PC" section?