Modify for b2c to b2b change

Kollipara Sundaraiah (B.com) (2984 Points)

13 June 2020  
one of gst registered dealer gstr3b and gstr1 filed up to march,2020.dealer mistake sales output b2b wrong b2c filed shown in gstr1 two months for 2019-2020.
how to modify producure change b2c to b2b gstr1 return in 2019-2020.