Banks usually allow three attempts to punch in the correct PIN after which your card gets blocked. If you find yourself in such a situation, you should call the customer care of your bank and tell them about the problem.
Some banks will verify your details and generate an OTP via SMS to help you reset your PIN. You can also access your netbanking account and reset the PIN. Banks like HDFC automatically unblock your card after 24 hours. You can then use your Debit Card to reset your password.