When you reinstall windows esspecially if you reformat and reinstall.
ALWAYS have a list of your devices and then go to those websites and download the latest drivers for ALL your devices.
Your sound drivers are probably located here:
http://www.soundblaster.com/support/(Unless you have some kind of different sound card)
ALWAYS go to the microsoft site and Update your Windows so that your OS isn't some kind bleed virual infections.
Most likely the combination of thsoe two things will fix your issue.