Open Start, enter Device Manager, and select it from the list of results. Under Sound, video, and game controllers, select your sound card, open it, select the Driver tab, and select Update Driver. If Windows doesn't find a new driver, look for one on the device manufacturer's website and follow their instructions.
If those steps didn't work, try uninstalling your audio driver: open Device Manager, right-click (or tap and hold) the audio driver, and select Uninstall. Restart your device and Windows will attempt to reinstall the driver.
If that didn't work, try using the generic audio driver that comes with Windows. Here's how: in Device Manager, right-click (or tap and hold) your audio driver > Update driver software... > Browse my computer for driver software > Let me pick from a list of device drivers on my computer, select High Definition Audio Device, select Next, and follow the instructions to install it.