Toshiba A200 No Sound - Help!

Hi,

I have a Toshiba A200 laptop for which the sound just stopped working about 6 months ago. I bought a USB sound device to attach and then connect to a stereo system which worked perfectly for the last couple of months. Since I have re formatted laptop I can not get sound no matter what I try

Have re-installed sound drivers and device is found and shows as working and playing sound but no sound comes out

Please help

Thanks