Remove (uninstall) the name of your soundcard from Device Manager, then re-install the driver. If you did not follow this procedure the first time that's probably why new driver didn,t work. You should always remove old driver from Device Manager before installing new one. If new driver still no good, do the Device Manager uninstall again, then re-install th old one.
If using XP, however (you didn't say), you can go to Device Manager, highlight the soundcard entry, select 'driver' tab then click 'roll back driver'. Windows should re-install the previous driver. This method may not work if you've confused Windows by trying to install several times, but worth a try.