With respect to your above mentioned query, we would like to opine that you can apply for revocation of cancellation of registration in order to have your old Gst. However, the decision rest with concerned authority.
For more information, please call us on 9820042562 or write to us on firstname.lastname@example.org or email@example.com.
GST number gets cancelled by the department on suo moto basis if the taxpayer has not filed the returns consequently for 3 months. So once the GST number gets cancelled, one can revoke the cancellation by filing form GST REG 21. Such form shall be submitted within 30 days of cancellation of GST Number. Before filing this form, it should be made sure that the required conditions such as all the returns must be filed till date and any other as mentioned in the notice of cancellation should be fulfilled.
To know about claiming refund on cancellation of GST Number do read: How to Claim GST Refund & Apply for GST No. Cancellation.