Another problem with my laptop: Sound not working

I am completely stumped. My sound doesn't work. This problem occurred within a 5 minute car ride from my girlfriend's house to my classroom.

What is weird is that I know that my speakers work, because when I start up my computer the "Asus" logo comes up and makes a noise that sounds something like fire. It's supposed to do that. But, when it finishes starting up, the windows logon noise doesn't go, and neither does any sound at all.

I thought it was a sound card problem, but the thing is that if I plug speakers or headphones in they work.

And it can't be a loose speaker wire because of the fact that they work when the computer FIRST starts up.



I've tried a system restore, and that didn't work. And I really don't want to try anything else unless suggested by someone who know a little more than me, haha. Please help!