Replying to COMPUTER HELP!

if anyone could help me that would be awesome, one day randomly my computer just stop playing sounds. it says there are no mixer devices or something installed like i have no sound drivers or anything i have tried to install a buch of sound drivers and all that but nothing is working. i have an HP comp and i run windows xp home if that helps at all. so if anyone has the solution to my probelm please help lol i really wana be able to hear sounds again