External HD not mounting (com.apple.DiskManagement.disenter error 0.)

macOS Catalina, v10.15.7

27" iMac - Late 2012

I had made a Time Machine back up by accident on an external drive with all my files and when I tried to delete the Time Machine back up with Time Machine it started to delete but then a message popped up on the screen that the HD was not ejected properly.  Now the external HD is unmounted.

Tried mounting it with Disk Utility, but it gives me this message "(com.apple.DiskManagement.disenter error 0.)"

Any help would be appreciated. Thank you.