WD external drive not mounting, Disk Utility issues

Has my external hard drive had it?

Im a WD external harddrive that ive had for a few years that I use to back up my machine to. I split it into 3 separate volumes and use CCC to duplicate files to them. One of the volumes I used to clone my hard drive to, and looking today it no longer mounts on my desktop. Also, when I go into Disk Utility none of the hard drives volumes show up at all (even the 2 that show on my desktop). and in fact, when the drives plugged in - Disk utility refused to actually show anything - even my internal drive.

Im guessing the hard drives had it - but was wondering if there might be any other reason for this happening? Is there some kind of encryption/password process or something that its not passing maybe?

any help much appreciated

thanks

Nick