MIS intraday trades need to be square off at the end of the day and seller should be available at that time. Stocks with high volume don’t face this problem but it can arise with low volume stocks.

If there are no buyers, it means that you can’t sell. You would be forced to take delivery of these shares to your demat account. In case you dont have a demat account, you could ask your broker to sell it the next day on your behalf

If you do not have the margin and your broker too hasnt been able to square off then the only option is to take delivery. Now unless the quantity of your order is huge, the broker will take delivery in his pool account and sell it off later.
The real issue arises if you have a short sell position and now you will not be able to deliver the stock. Hence in this case you will be taken to auction market due to short delivery. But in this case the worst scenario will be that your broker charges you penalty/ interest. However this is a very
rare possibility.

Currently everyone has to open demat account in India for trading in markets.