It would appear that you probably need to reinstall the sound card's driver, davo1967, that's the usual cause of no sound after a reinstall of Windows. Maybe you have those on a separate disk that came with your PC? If not, let us know the make and model of your sound card/chip. You can find that out by doing a scan with Belarc Advisor, you can download that if you click here
How did you connect to the internet prior to the reinstall? Did you use a modem, a router, was it wireless or wired?