Your problem is a different one to mine and, unfortunately, sounds expensive and probably terminal. The symptoms sound very much like what happened to my old external drive which was not a WD product. Almost certainly there has been a failure to the internal read head that picks up data from the drive and it is physically touching the surface of the drive. The worst thing that you can do under these circumstances, as I discovered to my cost, is to keep trying to read the data as this simply makes the damage worse. I paid a specialist recovery firm here in the UK their standard charge of £205 to dismantle the disc and try to recover the data, but without success. Here is their diagnosis: “Initial problem on the hard disk was read/write head failure, although this did not cause any media damage to start with, it seems the hard drive was powered on for a period of time after the read/write head failure which caused media damage on the disk platters.” They could only restore 8% of the data which was not enough to be useable. In the end I lost all of the data that I had backed up and had to resort to recovering what I could from my current PC and two previous PCs that, fortunately, I had kept and not thrown away.
The initial problem with my new WD My Passport was eventually resolved when I tried for a third time to restore the drive to its original factory settings and reinstalled it. It now works fine although the back-up process seems quite slow considering that the size of the most recentl back-up is just 35GB. I’ve resorted to using the Back up and restore function within Control Panel on my Windows 7 operating system which is both more intuitive and faster.
Good luck and remember, it may be better to use the Cloud to back up in future.