Pls help hve dell inspiron 6400 no voice mixr

Hello,

I, have dell inspiron 6400 laptop, in that i have height defination audio device with no sound mix. so tht iam not able to play songs in paltalk, or yahoo rooms. I tried sigmatel height defination audio driver also but it is not working. iam trying to download sound drivers from long time from 1 yrs still no sucess.. so any one know how to download for my laptop sound drivers with audio mixer to play songs in yahoo chat rooms are any other chats rooms pls help me out. sicne one week iam try very hard .. at last first time iam posting to any one for help. this my first site for my post .. if any one know pls help me out ok.. my id is champaleem@gmail.com .. waitng for replies.. pls help me....................... thanks in advance..