Know more about TDR rules

If the above mentioned steps don't work,
1. Tap History on your PhonePe app home screen.
2. Select the relevant payment.
3. Tap TDR.
You can close/exit the app and try again.

You can also check the rules listed below to confirm whether you are eligible to file a TDR or not:
1. The confirmed passenger should not have travelled.
2. The train is late more than three hours and the passenger has not travelled.
3. The train has diverted from its route and it is not reaching the boarding station.

Depending on the reason, there is a timeframe to file TDR. It could be possible that you have crossed the TDR-filing time limit. Please check this link for more information on TDR filing rules:
Link