In terms of Rule 138E (a) and (b) of the CGST Rules, 2017, the E-Way Bill (EWB) generation facility of a taxpayer is to be blocked, in case the taxpayer fails to file their returns in Form GSTR-3B or Statement in Form CMP-08, for two or more consecutive tax periods. For unblocking of this facility, taxpayer need to apply to jurisdictional Tax Official in Form GST EWB 05.
Source Taxguru
See also Form GST EWB-05 filing to un-block E-Way Bill generation facility