The way I can see is your drive’s file system is corrupted.
Check/Do the following: (Do not run Windows Scan Disk)
Important: Improper/Loose USB connection is suspected: Use newer PC or well known/clean USB socket for the following procedure.
1) Download HD Tune basic and test your drive. (Benchmark, Health and info)
2) You might see some warnings on health page.
3) Now run “Error Scan” (Uncheck Quick Scan). This may take several hours depending on your drive size.
4) If there are damage sectors on the drive, you should see red blocks. Wait until complete the test.
5) Exit HD Tune.
6) Try to copy and backup whatever the data on that drive.
7) Delete and create new partition(s) on your drive using disk management under “Computer Management” consol. (Rignt click My Computer icon and choose Manage)
8) Now download HDD Regenerator 2011 Trial. (Google for $0.00 full version)
9) Run Pre Scan fully and then run repair scan. (Takes hours – depending on your drive size)
10) While scan, HDD Regenerator will report errors found and or corrected.
11) This should fix your problem. – Read info on HDD Regenerator 2011 website.
I have successfully corrected my WD Passport Essential SE 1TB by following above method.