Go to your bank and ask for a copy of your credit card payment history. Look throught every detail that you can remember that are bad if you don't have any note about how much, when you use your credit card. Deny anything that you think is not appropriate so they will check for you. Start with the newest bad debt and work back to the oldest. The older the debt, the less impact on your score. Contact the collector and negotiate settlement.

How to fix bad credit card (stolen)?