You really need to discuss your situation with a qualified immigration attorney.

Had he entered the country legally, you would have only needed to file the I-130 and I-485 on his behalf to adjust his status and get the green card process rolling.

How long ago did he live here illegally? Under what circumstances did he return to his homeland? Was he deported? Was he threatened with deportation and returned voluntarily? Or did he just head back home without any prodding?

Since he overstayed for more than 180 days, he triggered the 10 year ban.