Windows 10: Flash drives recognized but external hard drives are not

My Windows 10 Home laptop will recognize all of my flash drives but won't recognize any of my external hard drives. They all use to show up but now they aren't. The hard drives show up in disk manager but won't show up in file explorer. I hooked them up to other laptops & they all show up. I've tried uninstalling drivers & reinstalling them but It hasn't worked. Any ideas?

:)

 

Automatic backups

trying to setup automatic back up to external hard drive:

when entering "update & security" then backup it gives the option to "add a drive". It recognizes a removable sc card but does not recognize my external hard drive. The file manager does recognize external hard drive.

How can I get the drive recognized in "add a drive?" I have formatted the drive using ntfs.

 

What about bluetooth3+HS in Symbian Anna ?

An N8 can recognize a big external hard drive, the largest tested that works is a 250Gb external hard drive. The problem in recognizing is if the hard drive can be powered using the measly output of an N8.

 

In Disk Management do the External USB drives have a drive letter assigned? If not they probably won't show in File Explorer. I keep 3 such drives connected always and they have drive letters, the USB Thumb drives I plug in automatically get a drive letter assigned and then can be seen in File Explorer.