My Acer Windows 10 notebook had a 1 tb Toshiba internal hard drive. A few months ago I replaced that hard drive with an SSD. I now use that hard drive to periodically clone the SSD back to the hard drive for a full backup. During that process, the hard drive is connected to the Acer by a cable from the hard drive to a USB port. All has been fine until last night when the clone process didn't complete. I then found that the plugged-in hard drive didn't appear in File Explorer (it had been drive E). When connected to the USB port, I can feel the disk operating but it's still not being recognized as being connected.