And see if there are any Yellow ? in the list of Installed Hardware. This means that the Driver for this software isn't working or has been removed.
As Realtech doesn't send in their drivers fro Digital Signing to M$ it's also possible that some new Patch has broken the drivers for your AC 97 Sound Card. Or if you have a certain type of Plug In Board for the Sound Jacks it could have failed.
As you haven't provided any information on your hardware it's very hard to say any more but for starters check the device manager and if there is nothing listed there as not working check the In Put Jack for the speakers they should be plugged into a light green socket.
Of course if you are not using some form of Windows I would be looking at a straight Hardware problem so the Speakers, Sound Card. Adapter would be the first place to look.
If you post back with more information I'll try to help you resolve the problem.
Col