If you have lost or misplaced your Declaration of Intention, Naturalization Certificate, Certificate of Citizenship or Repatriation Certificate, you may submit form N-565 to the US Citizenship and Immigration Services offices to receive a replacement. The form is two pages long and only requires a bit of biographical information.
Fill out form N-565, which you may download from the USCIS website. Personal information and information about where you received your original certificate is required. Attach a copy of your lost certificate if you have one.
Include two standard passport photos, which are available from national stores or local photo establishments for under $10. Write your Alien Number and name on the back of both photos.
Write a check for $345 to "Department of Homeland Security". Check the USICS website for current fees.
Mail your application, photos, copies and check. The USCIS has two different processing centers, and you must send your package to the correct one based on the state you live in. Consult the accompanying instructions for the correct address.
Wait between 4 weeks and 6 months to receive your replacement certificate.