If you are overseas, you must report the loss of a United States passport to the nearest US Embassy or Consulate as soon as possible. They will instruct you as to how to replace it. The following steps will help you replace your passport while still in the United States
You may contact the State Department by phone at 1-877-487-2778 M-F from 8AM to 10PM,ET. This will invalidate your passport. Once a passport is reported missing, it cannot be revalidated.
If you are not applying for a new passport, you can notify the State Department of your loss by mailing a completed Form DS-64 to:
US Dept. of State
Passport Service
Consular Lost or Stolen Passport Section
1111 19th Street NW Suite 500
Washington DC, 20036
You may appear in person at a Regional Passport Agency or any Acceptance Facility(usually a post office) to report and replace a lost or stolen passport. You will need to fill out and submit forms DS-11 (Application for Passport) and Form DS-64 (Statement Regarding Lost or Stolen Passport)
To replace a passport you will need the following documentation:
Proof of citizenship-Birth certificate with raised seal or Certificate of Naturalization is acceptable
Identification-Driver's license or State or government issued ID card
2 passport photos(2x2), available at most drugstores.
Social Security number
Fees are currently $75 for the passport and $25 to the Acceptance Facility. There is a $60 fee if you want expedited (faster) processing. They may only accept cash or credit cards, not personal checks.
Take these forms to a post office that has a passport office to begin the process. If you need the passport because you will be traveling in less than two weeks you will need to make an appointment with the Regional Passport Agency. Bon voyage!