I hope some one with expriance can figure this out.
MY portable HDD is not recognise on my computer or Disk Mangment.
On the Device manager it shows as unknown device (not yellow), I try to uninstall and scan for changed hrdware, update drivers it is still not showing up.
I strongly recommend you to check the drive on another PC and with another USB cable.
Try connecting the drive to a Linux OS. If you do not have that option, burn a Linux live version. It can be freely downloaded. Boot it from a USB drive and connect the drive. The drive might be recognized giving you a chance to backup all data. Let me know if there is any progress!