What should I do if the receipt notice could not delivered and return back? If they that have given an appointment already and I’m not sure if it is also not delivered the appointment letter , so will I get an biometric appointment again. Please help me
You can walk in to any close by Application Support Center and then request them to take biometrics. They should be able to look up your case and then take biometrics.
Call USCIS as well on this. Check user experiences in comments and article at