If you suspect that you have become a victim of identity theft you should move quickly to prevent further intrusions into your personal information and your financial accounts. Begin by calling the toll-free fraud number to one of the three nationwide consumer reporting companies (numbers available on the side of this page) and asking them to place a "Fraud Alert" on your credit reports.
A Fraud Alert will put in place a 90 day period of advanced protection measures on your accounts. Creditors will be required to follow extra procedures before opening new accounts in your name or making changes to your existing accounts, hopefully preventing further breach of your accounts.
Additionally, filing a Fraud Alert entitles you to one free credit report from the three credit reporting companies (Equifax, Experian, and TransUnion). Check this free report for inquiries from companies you haven't contacted, accounts you didn't open, and debts on your accounts that you can't explain. If you find inaccurate or fraudulent information, contact the consumer reporting companies to get it removed.