What to do if GST Provisional No.is Cancelled

I have submitted my returns till February 2018, but after that I was not able to login to my GST A/C later in the month of April, I found my GST No. has got cancelled.
I complained to the customer care also, but they ask me to contact the nearby Charge Office.
When I went there the Joint Commissioner told me that they are looking into the matter. But still nothing positive has been done.
Pls help