It's the headache you'll remember the rest of your life: You've flown somewhere for business or pleasure, but midway through your trip, your identification gets lost or stolen. What do you do?

To some extent, the answer depends on whether you are in Berkeley or Bucharest. But no matter where you are, it is important to take action the moment you discover your ID is missing, whether it's your driver's license or your passport, because it could take some time to get the matter straightened out.

What follows are specific instructions and tips regarding both scenarios. Print this out and take it with you, or bookmark this column for future reference. It's good information to have on hand -- just pray you never have to use it.

Losing your ID while traveling outside the country presents a completely different set of issues and problems than you'd face if you lost it within the confines of the United States. Follow these steps to make recovery as painless as possible.

Find the nearest consulate or embassy. Once you learn your passport is missing, immediately contact the nearest consulate or embassy. (The Department of State's Web site has a comprehensive list.)

Know the hotline numbers. If you don't have the list or can't get to the consulate, contact the Department of State's Overseas Citizens Service. From outside the U.S., dial 1-317-472-2328. If you are in the U.S. trying to assist a family member who is traveling abroad, call 1-888-407-4747 toll free for assistance.

Prove your identity. During an interview with a consular officer you will be asked to provide basic personal info, as well as your passport number and date and place of issue, if possible. You will need to supply the names of identifying witnesses at home and abroad; if you are traveling with others, they can be asked to vouch for your identity. In certain circumstances, you might need to have someone back home fax copies of identifying documents, such as a birth certificate, to the consulate. For this reason, it is a good idea to leave copies of these documents with family or friends. If there are no unusual circumstances, this part of the process goes very quickly.

Reapply. Once your identity has been verified, you'll have to fill out a new passport application, as well as an affidavit regarding the loss/theft of your old passport. If you believe your passport was stolen, you might have to file a local police report.

Pay the fee. Your replacement passport will cost at least $85 (an additional $60 expediting fee may be assessed as well), but it will be valid for the usual 10 years. If you lost your credit cards and cash along with your passport and have no way to pay, you'll be issued a temporary passport for free just to get you home.

Accept a conditional passport. If the Department of State has lingering doubts as to your identity but is satisfied enough to let you back into the country, they'll issue you a conditional passport. Once you get home and can provide them with the proper documentation, you can have the passport validated for the full 10 years.

Bottom line: Always carry a photocopy of your passport. Always. It's the next best thing to having your actual passport. But don't carry it with your passport or with any other travel documents -- put it at the bottom of your suitcase and leave it there. But even that might get misplaced, so as a backup consider scanning your passport and downloading the file onto your laptop or other digital storage device, such as an Apple iPod. If you don't travel with a laptop or an iPod, email the scanned image to yourself (both as an attachment and inserted into the body of the email) and let it sit in your inbox unopened. Either way, you'll be able to print out a copy of your passport from your hotel's business center, an internet caf?, or any other location that has Web access and a printer. (Use the same trick for your driver's license when traveling domestically.) For more on what to expect if you've lost your passport, visit the Department of State's Web site.