It sounds like you’ve done pretty good at troubleshooting it already. The only other thing that I can think of to try is to use another power cord in case this one isn’t working properly. If you have another WD product, you can check the power adapter, most My Book drives use the same power output so the power supplies are interchangeable. If not, You can try purchasing one through our tech support (if its available in your region since I’m not sure where you are located.
Otherwise it sounds like the drive may have failed. If you need the data on the drive then you may need to check with a data recovery company to see if they can retrieve the informtion for you.
Contact WD Support
http://wdc.custhelp.com/app/answers/detail/a_id/1048
Data Recovery Partners
