Hey there Harsh 3,
I'm sorry to hear that the Chromecast is not working out for you. If you've bought the device via the Google Store, check out this article on how to return an item. If you bought the Chromecast from a retailer, you'll need to contact them for instructions on how to return the device to them, as every store has differing refund policies.
I look forward to your response, and if you have any other questions or concerns for me, please let me know.