If your credit or debit card is lost or stolen, first report it to your card issuer and follow their instructions. In some cases, they will want you to report the theft to the police, or they will simply desactivate your card and send you a new one.
Be sure to note your card numbers and the customer service phone numbers, printed on the back of your card, and keep it in a safe place separate from your credit card.
Report your lost or stolen card as soon as you notice it is missing.
Keep track of where your cards are, and do not leave cards at work, in a hotel room or even in a locked vehicle.