Myntra.com — nike shoes return rejected

Hi i placed an order for a shoe. It came in a cardboard box. It was not nike authentic box. I placed a return and i was at office during the return. He rejected the return saying tags missing. I had got the product in same way only then i placed the return.
Kindly investigate on this issue. Myntra people are saying that it cannot be done since already it is closed. I am. Not ready to take the blame for myself and will. Not bear the cost.