What Happens if I Lose My Certificate of Naturalization?
A certificate of naturalization, once it’s lost, can be replaced.
There is an application that you can find online at the USCIS website, and it takes anywhere from three sometimes to nine months, depending on how busy they are, to reissue a naturalization certificate. Typically, if someone is sworn in in a big city, they are also sworn in to become US citizens by the court, in federal district court in where they reside. The federal district court also has copies of their naturalization application, and that can be obtained from the clerk of the court of where they sworn in.
Another way is, of course, once, usually typically, if somebody applies to become a naturalized citizen and they obtain their citizenship, they will apply for a passport. So a US passport is also proof of being a US citizen. But insofar as the actual certificate, once it’s lost, there really is no alternative but applying again to get that replaced.