I had paid an amount of 36,500 to csab 2019 special rounds.i didn't have allotted any seat in both the rounds .when will exactly the fee refunded?what should I do?

The official website states that the participation amount will be refunded to the eligible Candidates to the same bank account the payment was made from. Please check if your name is in the Eligible Candidates list and if you have updated your Bank Account Information. If you meet both the criteria, then please write to their helpdesk at: csabhelpdesk@nit.edu

It's a governmemt process, so it takes a significant amount of time. If you do not receive the refund within some time then you should address this matter to the appropriate authorities by post or by mail while clearly stating your issue and request them to process your refund as and when possible at the earliest.