My pc have no sound.

Hi..

When you are formatting the PC all the motherboard function are lost. Check first the software if it is already installed. You need to install the motherboard driver so that the sound, video graphics, USB, LAN card and other part of motherboard are functioning, Load you installer CD to the CD room and install.
After that it's bring you to restart to take effect and get functioning.

Thanks for using fixya

Regards

ICmanServer

You'll have to reinstall the drivers for your sound. See this tutorial. You can download the drivers from HP, or the mfr. of your sound card.
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