I made a deposit by check/cash and received a receipt, but the bank says that its records do not reflect the deposit. Since I have a receipt, doesn't the bank have to credit my account?

You should contact the bank and provide a copy of the deposit receipt. However, the deposit receipt is not conclusive evidence that you deposited the funds.

If the deposited item was a check, you will need to contact the party that provided the check to you and obtain a copy of the front and back of the check. If the deposited item was cash, and the bank does not agree to honor the receipt, you will need to seek legal assistance regarding any legal remedy available.