If you are living in India you will need to download the app called Zebpay where you can buy bitcoins.
After the banking ban of 2018, Zebpay moved on its headquarters to Singapore and completely closed down its INR trading pairs. Thereafter, Zebpay was functioning more or less like a crypto wallet for months and later on created their crypto to crypto trading exchange. Recently after the removal of banking ban by the Supreme Court, Zebpay has announced that they would be relaunching their services in India with INR deposits and withdrawals. Apart from that, there are far better exchanges like WazirX which has joined hands with Binance for the announcement of its IEO and integrating of INR in Binance. After the removal of ban, unocoin (one of the popular Indian exchanges) has started accepting INR deposits and withdrawals.
For quite some time I have been sticking onto lbc trades which seems to be promising for me to an extent. I would trade with people quite often and practicing P2P trades are faster while we are in need of btc. So, if we are in a need to buy btc in India we could opt for WazirX, Unocoin, CoinDCX and LBC. I have created a topic which lists most of the exchanges where we can buy bitcoins through INR :
Bitcoin Resources - Consolidate List (India Specific)