Sound not working

Hi I usually work with my sound on mute, using the button top right on my key board. Today I went to unmute and it wouldn't work, the icon on my screen still shows that it is muted. I then right clicked to see if there was a problem and the trouble shooter says that the device is not installed. So I found my realtek sound driver and it says it's installed. I then went to the Realtek site to see if I needed an update for the driver, I downloaded and installed it, to a point, but a message comes up saying that there is no device for this driver.

Now yesterday I used my "winzip system utilies suite" to do some maintenance, which I do about once a week. It cleans out the registry and checks for driver updates. I'm not sure if this may have caused the problem or not, but I'd appreciate any help in getting my sound up and running again.

As an extra bit of info, in case it helps, somewhere along the line whilst trying to sort the problem, I clicke don "levels" and the new page was blank, and also when I was in windows help, I tried to click on "click here to open volume control" but nothing happened.

Thanks all. Anya

Hi Just to let you know, that I went back to restore point that was before I did my maintenance and the problem is resolved.