GSTR-1Wrongly Filed

i field gstr 1 for the month of may in that , i have sale goods to party and raised bill and file gstr1 after month of end we have file 3-B but that time party given goods return without Dr/cr not at a time what can i do bcz allerdy i have filled gstr1. and what about mention in 3-B and next month GSTR1 effect. plz sir gaid mi its a urgent matters...