Why do I have no sound and my DVDs dont work

I have a iBook G3 Snow 600 MHz 256 MB, and the sound doesn't work. I got it to magically start working once when I booted up Oregon Trail, but when I turned it off and back on it stopped working again. When you plug in headphones you hear staticy noises and faintly hear whatever you're listening to. When you put in a DVD the DVD player just shows a green screen and says "not permitted". I assume that the DVD thing and the audio thing are related since they started working at the same time^. I'm thinking this has something to do with the logic board or the CPU but if anybody knows why id love to know, even if its expensive and complicated to fix i'm still willing to consider doing it