Rachel,
I have the exact same problem that you have. No sound. I have tried
everything. I am going to take my computer to the Best Buy Store and let the
Geek Squad fix it.
What you do is of course up to you, but I have three comments for you:
1. Of all possible sources for getting your computer fixed, the Geek
Squad is probably the very worst.
2. In general, whether it's Best Buy, or any other Big Box store, Big
Box stores are the worst place to use for trying to get your computer
fixed.
3. The best places are usually small, local, non-chain computer
service people. Even with those, it's best to get recommendations from
others in your community who have used them successfully. If you have
a PC Users Group in your town, getting their recommendations would be
excellent.