1. first verify your drive is faulty or dead... check in another system and check power connectors.
2. after all those if it is still faulty first go to this ----
WD Support / Warranty Services / End User / Product Replacement for End Users
3. click standard replacement(india)
4. click continue on next screen after you have followed the steps there(mainly checking the HDD again which you should have already done)
5. give them all the information needed namely serial no and model no, your address etc.,
6. after all this they will give you RMA no. note this down and click on print a sticker or print button which will give you the address of the RMA center.
7. they will generally schedule a pickup by themselves or you may have to call their customer care to schedule a pickup... no is 18002005789 or 01126384700
8. Pack the HDD properly in a box and make sure that it is cushioned properly and does not get damaged in transit.. and stick the labels as per the instructions and write your serial no and rma no on 3 sides.
9. Wait for pickup
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in my opinion send the HDD through courier(DTDC) by yourself so that you will have the new HDD by next week or so otherwise they take their own time to pickup.