Help, My 1TB My Book HD is not recognized

Hi all,
I have a very serious problem with my external hard drive. I accidentally unplugged the usb cable without ejecting the drive, now it is not recognized neither in windows nor mac. when I opened disk utility in mac i get this information:

Disk Description :disk1
Total Capacity : 6.98 EB (6,979,792,214,784,740,000 Bytes)
Connection Bus : USB
Write Status : Read/Write
Connection Type :External
S.M.A.R.T. Status : Not Supported
USB Serial Number : C14251553F88F54E598F291C32112D
Partition Map Scheme : Unformatted

I couldn’t repair the disk as the option is grayed out in DU and I can’t erase it, restore it or partition the HD as I keep getting the error:

"POSIX reports: The operation couldn’t be completed. Invalid argument "

I have a WD My Book 1TB for mac, Model NO: WD 10000H1U - 00
Please Help. Thanks.

Upgraded router to (Netgear6000).  Same thing , no computers see it.  NoCD to reinstall either.

I would suggest that you try it on a pc for better trouble shooting what is the exact modle of that drive?