what's wrong? my pc just re-formated and no more sound. help plse???

install the driver that comes with your pc. or go to my computer, system, hardwares and check if there is any quesiton mark. use update driver to install appropriate driver for audio

This problem usually happens when you reformat hd and re-install OS.

Your sound card is either embedded in the motherboard's chip or you have to download the sound card driver from the sound card's brand name website to reinstall the sound card driver.

If it is embedded in the motherboard chip (Intel for example), then you need to get the chip version and go to the Intel website to look for all the updates for its drivers.

To look for the chip version, when you boot your computer up, press delete + F1 (or F2) to go to the boot menu and you will see the chip version there.