You may see no money in your available funds because of auto-settlement. As per SEBI regulations, all brokers must transfer all unused funds in your trading account back to your bank account on the first Friday of either the month or quarter. This may also happen if your Share.Market account has been inactive for a long time.  

You may see a lesser amount in your available funds because regulatory charges have been deducted from your trading account at the end of the day. You can go check your cash ledger to see the detailed breakdown for this.