Then maybe the driver isn't the problem. What happens when you install it? Nothing? Do you just have no sound? Do you get an error message?
Have you gone to Start-->Control Panel-->System-->Hardware tab-->Device Manager an checked to see if you have any yellow "!" or Red "X" next to any hardware entries?
What brought about this problem? Did you recently reinstall your OS? What are you using for an audio out? Laptop speakers? Headphones? PC Speakers? Is it possible the volume is just not turned up?