Ok, you NEED to answer these questions.
1. Is ALL of your sound not working? Can you hear anything through headphones or the speakers if you turn them up?
2. Did you personally install windows 8 or did you buy the computer with Windows 8 on it?
If you can't hear anything at all (and actually try different websites, different computer programs, not just one thing)
1. Did you install any updates at all prior to the sound not working?
2. What versions of Java do you have installed?
3. Did you try a system restore back to a point when your sound was working?
4. Have you tried googling the problem?
5. Is your sound driver installed/up to date? (most likely the problem if you installed windows 8 yourself)
In my experience, when my sound has stopped working, doing a system restore helps.