Contact your bank immediately. You are lucky that you detected it right away. Time is of the essence. In the case of an ATM card, the bank will have you fill out a few forms, and investigate the problem.I had this happen a few years ago, but was able to catch it in time. This is why you should never pay bills or do your banking on line.

In cases of credit card fraud you have 60 days to make a written complaint to the credit card company. During that time the credit card company will begin a full investigation. The transaction is reversed for the period of the investigation. Following the investigation the credit card will either reverse the transaction permanently or charge your account depending on the results of the investigation.

In the case of forged checks, the bank maintains signature cards for your account, and ultimately is liable for paying off on checks with a forged drafter's signature of forged endorsement. I had this happen to several clients. The banks were not happy about paying the claim to the depositor, but they had no choice. The bank then goes after the forger.