Sorry to hear that. Any number of things could have happened. Please do the following checks,
1. Check the error message that appeared on the ATM machine screen and take steps accordingly,
For e.g. if error message is,
"Network connectivity failure" --> Please try again
"Invalid PIN or Invalid Authentication" --> Please try again with corrent PIN or if you do not remember your PIN, you can Reset your PIN and try again.
2. Check if your card is termporarily blocked. You can unblock your Debit Card using following steps
On Net Banking:
Login to Net Banking
Select Debit card
Select Deactivate/ Activate card
On Mobile Banking
Login to Mobile Banking
Select Service Request -> Debit Card
Select Activate / Deactivate Debit Card
2. Check for any physical damage to your debit card like scratches & cracks on the magnetic strip or the chip
3. Check daily transaction limit of your debit card.
4. You can check & update the primary account number linked to your debit card by following these easy steps,
On Net Banking:
Login to Net Banking
Select Debit card
Select Change Primary/De-link account.
On Mobile Banking
Login to Mobile Banking
Select service request -> Debit card service Requests