By law, every applicant for naturalization must attend and be interviewed. If you fail to appear for any immigration benefit for which personal interview is required, CIS will deny your case for lack of prosecution. If a notice was in fact not sent, you can request a Service motion to reopen. You will not have to pay the usual motion fees. If you cannot show Service error, you can still file a motion to reopen and for good cause, the motion will be granted. You will have to pay for this. A denial for lack of prosecution is not with prejudice and you can re file your N-400 as soon as possible. The ultimate course of action will depend on what makes you comfortable.
Answered on Feb 04th, 2013 at 7:08 PM