Sales return igst hereafter no sales in igst

I have sold Other state  sale on December 2018 for Rs.236000/- IGST - 45600/-  Only One Bill all my bill are local sale only and  hereafter no otherstate also now the the party form othersate return the goods on march 2019 for Rs.236000/- IGST - 45600/-  in GSTR - 3B how can i get the reverse tax of IGST kindly do the needful ( Can i add the IGST return amount in ITC of Intergrated Tax )