If you missed your train due to any reason and could not cancel your ticket before the scheduled departure time, then unfortunately you will not be eligible for any refund from IRCTC or Indian Railways.
However, if you had a confirmed reservation and the train was canceled by Indian Railways, or it was delayed for more than 3 hours at the journey originating point, you may be eligible for a refund. In such cases, you can file a TDR (Ticket Deposit Receipt) request on the IRCTC website within a specified time period and the refund will be processed accordingly.
It is important to note that TDR requests must be filed within a specified time frame and you need to provide valid reasons for your refund request, which will be verified by the concerned authorities.
I hope this information helps.