no sound device

I have had Windows xp for over 2 months. Now, all of a sudden, my I have no sound. When I checked on it it says I have no sound device. The only thing I can think that I have done recently is install quick time because I needed it for the short moview with my digital camera. I don't know if this problem started then or not, because I often have my volume turned all the way down--soo I don't know the exact moment it disappeared. Any ideas how to fix it? Thank you

 

the first thing i would try is going to windows update http://v4.windowsupdate.microsoft.com/en/default.asp (it's in your start menu) and just seeing if the site can restore your sound driver. I'm assuming that it's your sound driver that is bad. and the site will restore it for you.