To reschedule your interview, you will have to go directly to a USCIS office
and speak to an immigration officer and explain your difficulty. If not,
you may send a letter to the immigration officer, if you feel that you may
not be able to appear for the interview. Remember that you will have to show
that you cannot make it for the interview for reasons beyond your control.
If you are not prepared for the interview and if you say that you are not
ready for the interview, the immigration officer may not accept your request
to reschedule your interview.
If the immigration officer considers your reason, your interview may be
rescheduled and you will receive a new interview notice. However, you must
not skip the interview date and if you do so, your US citizenship or Green
Card application will be denied. It is wise to appear for the actual
interview and if your situation does not permit you to appear for the
interview, you may reschedule it. But the USCIS will accept your request
only if the reason is strong enough. If your request is considered you will
receive a new interview notice from the USCIS. You will have to start over
again, if the USCIS does not accept your request.