First try these troubleshooting steps:
Try a different port
Try a different cable
Try a different computer
Verify the drive light is on
Try a different power outlet (Desktop Drives)
Plug adapter directly into the wall if in a power strip (Desktop Drives)
Verify that it the drive feels like it is getting power
For additional troubleshooting steps select your operating system:
Try the following Steps:
Hold the Windows Key () down and press R
Type compmgmt.msc into to the run box
Select Device Manager on the left
First check disk drives in the middle window
If you see the drive is detected here continue reading. If not, click here
Right click on the external drive listed under Disk Drives
Click on Properties
Click on the “Volumes” tab
Click on Populate
Document the disk number provided in this Window
Click on Disk Management on the left hand side
In the middle towards the bottom locate the disk number from earlier
Once located you will want to look for the following:
Does it say RAW or Unalloctated?
If the drive says RAW or unallocated and you have already tried a different port, cable, and computer but you need the data then you will want to consider data recovery.
If the drive is formatted correctly for Windows you should see the following information:
NTFS - If NTFS is missing then the file system has become corrupted. You can format the drive if you don’t need the data.
Capacity - Check to see if the drive is correct for example if you have a 1TB drive it should say 931GB.
Drive letter - Verify that the drive has a drive letter. If it is missing verify that other drives have a letter. If other drives have a letter but the external is missing then you can right-click and select change drive letter or path.
Click Add then assign a letter and OK
Within device manager look for unknown device, other device, or mass storage device with a yellow ! icon. Make sure to expand Universal Serial Bus controllers too.
If you see an unknown device or other device then right-click and select properties.
Under the general tab locate ‘Device Status’ and there may be an error.
You may see a code 10 or 28.
If you see Code 10 and have already tried another cable and computer then the drive has probably failed.
If you see Code 28 (this may work for others codes too, ie Code 43) then try the following:
Close the window with the code
Right-click on the device with the issue and select uninstall
Shut the computer down and disconnect the drive
Reboot with the drive disconnected
Plug the drive into a different port
You should see that it is installing device drivers
Once the driver loads check to see if it is giving the same Code.
Note: If that fails, you will need to try to reload the USB drivers for the operating system by inserting your Windows Media, rebooting, and attempting a Repair/Restore.
Warning: This can be dangerous to your data and you should disconnect your external drive before attempting this.
If the drive is not showing on your desktop or within Finder check disk utility.
You should see the drive on the left hand side
You should see two entries - the top with the capacity and one indented below that.
Select the indented entry for your drive and click on the “Mount” button at the top of the Disk Utility.
If the indented entry for your drive is greyed out then that indicates some level of file system corruption.
Select the indented entry and then click on Verify Disk.
Once the Verify Disk process is complete it will suggest you repair the disk or tell you there is nothing wrong with it.
If this is not the only copy of your important data, then try to run the Repair Disk process to see if it resolves the file system corruption.
If this is the only copy of your important data, then we suggest running data recovery software on the drive to attempt to retrieve your files.
If the Repair Disk process fails to repair the disk then you will want to reformat it to see if you are dealing with a physical issue or a logical issue.
Warning: Formatting erases all data on the drive.