You should apply for a replacement certificate if your current certificate is lost, mutilated, or destroyed. You may also apply for a new certificate if subsequent to issuance of your current certificate, your name has been legally changed either through court order or marriage or divorce.
Form N-565 is used to apply for a replacement certificate of citizenship or naturalization.
It is filed in person or by mail with the local USCIS office having jurisdiction over your place of residence (Except if you live in Maryland; file with the Vermont Service Center). It must be filed with appropriate identification to establish your identity and the filing fee. Current photographs meeting USCIS photo specifications must also be submitted.