Have gateway e4100 wont detect sound

have gateway e4100 use to have sound.formated a few times now dont even have speaker icon on tray.tried a few things not computer wiz.keeps saying no device.loaded 97 realtex still no.had a guy ho thought he could do it.ended up formatin again,he did a number.tried wizard no sound card.un blocked in directplay still nowent to device manager loaded drivers,still not typed dxdiag
no sound card detected.i must of deleated something but you think when i formated it come back but it hasnt.