sony aio s260 no sound

I installed Vista on my Sony Laptom VAIO S260. All went well except that I get no sound. I thought at first driver didn't install. But the driver indeed installed and function properly. In fact,when you play music, you could even see those indicators jumping up and down, meaning sound is being produced. It's just that it doesn't channel through the speaker. I installed Sony driver with no success. It seems like I have sound, but that the sound doesn't get to speaker. Does anyone have any suggestions?