GSTR 1 AND 3B.

One of my relative is in the business of supplier he didn't filed his gst R1 and 3B from 2017 july. he is a supplier goods and what ever he had purchase from the parties it is there 2A, but what ever sales he made from (july 17) till date he dont have thos bill and he didn't now them whome he mada the sales, simply i mean he dont have sale bills that he can present to me for filing his gstr 1, now how to file his gstr 1 and 3b.

pleases help me.