I am Shuchi from the Dell Social Media outreach team.In order to resolve the issue with the external USB Hard disk not detected by your system please follow these steps.
1)Check USB Connection:
If you External drive is USB powered, make sure that your cable is connected properly.
Try replacing the USB Cable.
If your external drive is powered through an adapter, make sure your adapter is working fine, replace and check, if necessary.
Try plugging your drive into another USB port.
2)This issue may also occur due to corrupt drivers. Please Install the latest USB and Chipset drivers from following links:
3) If the drive is still unrecognized, check to see if the drive appears in Disk Management
To open Disk Management, right click My Computer and choose Manage.
Double click on storage
Double Click on Disk Management
Ensure all of your drives listed here have a drive letter assigned to them,
If you see a drive that does not has a drive letter assigned to them
Right Click that drive
Click on Change Drive letters & paths
Now, add a drive letter here.
IMPORTANT: Choose a drive letter that does not already appear in My Computer.
Click OK to assign the drive letter and close the window.
Once assigned, the drive should appear in My Computer with the letter you have selected.
If the drive is listed as Unknown or Unallocated in Disk Management, the drive is not properly formatted for use with this computer. If the drive was used with a Mac or another non-windows device it may be using an incompatible format.
WARNING: Any data on the drive will be erased in this process.Please backup any data on the drive before proceeding.
If the drive shows Unknown, right click on the word Unknown and choose Initialize. Follow the wizard, accepting the defaults. The drive should now be labeled Unallocated.
If the drive shows as Unallocated, right click on the word Unallocated and choose New Simple Volume. Follow the wizard, accepting the default settings. Clicking finish will begin the format process. The format will generally take 10-15min, but can vary depending on drive size. When the format is complete the drive can be found under My Computer labeled New Volume.
If you wish to change the name of the drive, right click on the for the drive icon and choose rename from the menu.
In case the issue is not resolved or you need any further assistance please let me know.
Please feel free to contact me directly by sending a reply to this blog.
We would recommend you do not post your private information on a public forum.
Thanks & Regards
Dell Social Media Responder