If your passport is lost or stolen it is important to report it immediately.  If you are not immediately applying for a replacement passport, you should report it lost on-line (submit electronically) to the U.S. Department of State.  Please note that if you report a passport as lost, it is electronically cancelled, meaning you cannot use it again if you subsequently find/recover it. 

If you will be replacing the passport at the U.S .Embassy in Ljubljana, please also complete the DS-64 Report of Lost/Stolen Passport, print the form, and bring it to your passport appointment.

It is also a good idea to report the passport loss to the nearest police station.  Filing a police report will assist you if someone else finds your passport and tries to use your identity.