If somehow you've lost your State Bank of India (SBI) ATM card or your card has been stolen and you want to stop any misuse with your card, then you can do that by blocking your card.
All you've to do is just call 1800112211 and provide the necessary details to the SBI customer care representative and ask him / her to block your ATM card immediately.
So, what to do after blocking the card because you'll need an ATM card in the future also.
Contact your bank manager and apply for a new ATM card. You can also ask the SBI customer care representative to issue a new ATM card for you, after that you just have to collect it from your bank. Keep in mind, it will cost you some fee (service charges) depending on your bank.