My basement drain just recently backed up down stairs in the basement it was smelling horriable so we finally unclogged the drain.. an now we have that sewer smell still coming from the basement through our vents how can we get that smell to go away.. we tried everything please help

Your trap seal may have evaporated allowing sewer gas to escape. If the drain isn't used too much pour a quart of cooking oil or antifreeze down the drain to keep the seal intact, Good luck, Tom