Windows Vista Audio Problems

Hello,
I have a windows Vista laptop, I believe it was made in 2007. When I turn on my computer sometimes the sound works, and sometimes it doesn't. I've looked up online how to fix this, and I've gotten as far as "Windows audio" and changing the sound to "Automatic". The problem is is when I got there it already said "Automatic", so from there I'm not too sure what to do. Pleas help me, we've been trying to figure this out for a long time, and no matter where we look we can't find an answer to fix it.