My USB 3 external drive is now inaccessible. It's months old Seagate Backup Plus, 6TB, used in Windows 10. Now its only appearance is in the Device Manager, not in Disk Management, not detectable by all the Partition Recovery tools I have. I tried it on all the USB ports, on different computers, no luck. In the Device Manager, its Properties has an empty tab of Volumes, when Populate, the Error shows No volume information found. I also tried Disable and Uninstall the controller driver, and then rebooted, reconnected, for multiple times, no avail. Please kindly help.