Chosen Solution
At this point you two directions, first see if you can even ‘see’ the drive within your Mac’s Disk Utilities app. If you can then you have a good chance to use a data recovery app like this one: ProSoft Engineering Data Rescue 5 or shipping the drive out to a data recovery service like DriveSavers
Another thing you can try: Boot your computer with a Linux Live disk, and then plug in the drive. Linux might be able to read the drive. When I say “Boot with a Linux Live disk”, what I mean is, go to one of the Linux websites (e.g. www.linuxmint.com), download one of the current install files (one of the .ISO files), and then create a Linux install DVD with that .ISO file. Now boot the computer from the DVD you just created. Doing this won’t install anything to your computer (unless you specifically tell it to), so this is a very safe method of running Linux on your computer. Once in Linux Live, you can go to the Linux File Manager (it is probably called “Thunar”), then plug in your external drive to see if Linux can read it. If it can, then you can copy everything from it to another place.
Try use WD utility from WD web site. Check it. If it not help then use WINHEX trial version and check if you can see hard drive like physicl device. Try use R-STUDIO program also . it may help restore data. In Case If your drive size “0” or it asking you reformat it then use some WD data recovery service like : www.datarecoverywesterndigital.com