|That usually happens I'm afraid. You have to go to the Realtek website.|
In Device Manager go to your sound device in "Sound, video and game controllers". Right click the entry and you will see an Uninstall option. If you use this and OK your way out the drivers will re-install on reboot. This could fix the problem if their setup has got a bit screwed up.
You probably already know but there's a quick way to Device Manager - type devmgmt.msc in the Run box and hit the Enter key.
How to know you are getting old 1:
If you can remember when radishes tasted of something