Hello,
Check if the drive is seen in disk management on Windows or disk utility on Mac. If it is seen then you can format it from there.
How to partition and format a WD drive on Windows (8, 7, Vista, XP) and Mac OSX
If the drive is not seen in disk management or disk utility then its time to get it replaced.
How to get an RMA, (Return Merchandise Authorization) or replace a defective product under warranty
