|control panel/device manager/ sound, right click on each item and uninstall, also check remove drivers.|
then right click on the computer icon at the top and hit look for changes. or reboot.
if you have a bad driver it will be replaced and the old driver removed.
and the machine should install known working drivers.
however you may also meed to download the manufacturers chipset drivers including sound device from the medion web page
i hate computers!
but cant help myself....