Gst registration cancellation

You need to file Gst returns upto the date of cancellation (Including month)  no need for further return filing 

And also your right t collect gst from customers was lost from the date of submitting gst cancelation application

1).Suppose date of closure of business is 31st march, and all the returns till the month of march is filed. But application for cancellation was made in May. So Do I need to file NIL returns of APRIL ?

2) Already 15 days passed since application but no confirmation received from dept. What should I do?

1) YES 

2) Nothing done from your part wait for the confirmation from authorities