|You cannot, not unless you are willing to pay a cryptanalyst a lot of money to spend six months breaking the code.|
The instructions for the drive quite clearly state that should you forget the password the data is irrecoverable, lost for good.
Besides, even if it were possible you would not get much help here as we have no proof that you actually own the drive and are not trying to break into someone else's drive. People do that.
You only option is to contact WD and see if they can help but I wouldn't hold out much hope.