Dear Ms. Larkin,
Thank you for posting your request on History Hub!
If you know the city/state where your naturalization occurred, you can reach out to the NARA office that maintains records of the Federal court in that area. Here is a site that lists the courts and links to the correct NARA office: https://www.archives.gov/research/court-records.
In your request, please provide the city/state where the naturalization occurred; possible date(s) of naturalization; and full name you used when you were naturalized. If you let the staff member know you need a certified copy, they can facilitate getting you the necessary documentation.
You may also want to check FamilySearch’s web page on US Naturalization records for indexes listed by state.
We hope this information is helpful.