I reformatted my desktop, now no sound drivers?

I need download and install the audio driver but it's not on the mfg website. I have tried all obvious options and nothing works. Speakers do work because when I touch the little green plug to the metal, I can hear it in the speakers.
Lenovo 3000 H200 series, Windows XP home, SP2, Legacy audio. Like I said I tried everything, system settings, etc.