There are many passport issues that might arise when traveling abroad. The National Passport Information Center (NPIC) is your one-stop shop for solving these. They will be able to point you in the right direction and can be reached by phone at 1-877-487-2778. If yours is lost or stolen, you need to either contact them or submit a Form DS-64 to the US Department of State. In order to get a replacement, this document and a Form DS-11 will need to be submitted to an Acceptance Facility or Passport Agency.
To avoid serious passport issues, make sure yours is renewed on time. If yours is invalid, you will likely be denied boarding and will very likely not be covered by travel insurance. If you were over the age of 16 when yours was issued, it is valid for 10 years. If you were under that age when it was issued, it is valid for 5 years. Passports should be renewed around nine months before expiration in order to avoid problems. Certain countries require validity for a minimum of six months before the travel date. Also, if your passport is significantly damaged, it may need to be replaced in order to be accepted.
Anyone that needs a passport as soon as possible must make an appointment for a face-to-face meeting at a Regional Passport Agency. They will help you get one for international travel in less than two weeks or for a foreign visa within four weeks. If you have a life or death emergency in your immediate family, you will still need to be seen in person with proper documentation of the medical issue.
Finally, if you have successfully applied and not yet received your issued passport in the mail, you should contact the NPIC and speak with one of their customer service representatives. This should be done within 90 days of the date of issuance in order to avoid reapplication.