How to get green card again after getting it revoked

Hey so me and my dad used to have a green card since he married my step mom but then after some time they divorced and the green card was revoked since they thought the marriage was for citizenship purposes it’s been some years after that is there anything way we can get it back? My grandma is a us citizen and I heard if we can’t she can do a petition for us but we gotta leave the country how long would it take?