I think you can safely conclude that it's dead. This won't make you feel any better but, in twenty-something years of owning PCs, I've only had one drive fail on me and it was a WD Black, too. It was pretty traumatic - it was my only drive at the time, it wasn't backed up and the data was not recoverable. (Since then, I've maintained backups to the backups as well as periodically burning full images that I keep in a fire safe.)
The possible bright side is that if it was in fact sudden, it's probably a mechanical or electrical failure (might be something as simple as a faulty or burned out internal power connector) rather than data corruption or physical disk damage, which means the data is probably recoverable. I don't know what the recovery cost will be, but you can get estimates for free (aside from shipping costs) and if you use a WD-authorized recovery service, it will not void the warranty which, if I remember correctly is either 7 or 10 years (you can check the warranty with the serial number at the WD website).
I would give WD customer service a call or email and explain the situation. They might recommend sending to them first to see if it's mechanically repairable, in which case you won't need to do a data recovery.
Sorry we couldn't come up with a successful resolution for you.
http://support.wdc.com/recovery/index.asp