No audio device???

I just installed new Windows XP to my computer yesterday. And then there's no sound from my computer. I clicked the sound and audio devices in the control panel and it's said "No audio devices" All the volume controller is grey out and I can't adjust anythings.

From the device manager, in sound, video, and game controller, it is listed that:
Audio codec
Legacy audio drivers
Legacy Video capture devices
Media controll devices
Unimodem Half-duplex Audio device
Video codecs

All all the devices work properly. I think my audio device driver is missing. But I don't know what is my devices to download driver.

How can I know exactly what is my devices in my computer?? I have the problem to find out them and download the proper drivers.

I also have the problem with VGA driver (and I don't know what's VGA in my computer and I can't download its driver)

Please help my with this issue.

if u get an answer plz forward it to me to

thanks