I have a gateway and itwasall erased wheni got it I put windows xp on it but it says I have nosound it wont even show the littlebell sound all i knowis on the back it says model number mfaTXPNT MDW E4100 AND THE SERIAL NUMBER IS 0031813275 SO HOW DO i GET SOUND ON HERE?

go start in run box type devmngmt.msc device manager will pop up look at it n tell me if there is any lil yellow or red symbols next 2 anything