Dear @SunilSinha
To request a refund for your cancelled air ticket with Air India, you should initially contact your vendor or online booking platform to clarify the maximum time limit to initiate a refund.
If you still have any problems, request a refund online by visiting the online customer support page (airindia.com) of Air India and selecting the Refunds option. Further, follow the given instructions.
Finally, you can contact the Air India customer support team by calling at +911169329333 or 18602331407.
For more help, read: How to file a flight complaint to Air India?