How to Search for Schoolmates

Contact your school and ask if they can help you. The administrator might keep current contact details of past students or have an alumni association. Even if they can't give you contact information directly, they might be able to contact an old friend on your behalf.
Search your local phone directory for the name. Maiden names can change through marriage, but you might still find names of family members that you recognize.

Visit your local library to access resources such as a national telephone directory. Many libraries offer these services free of charge.
Search Facebook for your friends' names. As of 2010, 500 million people worldwide use Facebook, so you have a good chance of locating a name. You can use the "Filter by Location" option to narrow the search down to a city or region.
Visit social networking sites such as Alumni.net, Lost School Friends and Classmates to search databases for names. Registering for these sites also increases the chances that the person you're looking for will find you.
Type your friend's name into a search engine such as Google, Yahoo or Bing. Even if she doesn't belong to a social networking site, you may find clues such as mentions on other friends' websites or from local news sources.