How Do I Get My Headphones To Work On My Vista Os?

I am using vista, for some reason when i plug in my headphones to lesson to a song or video it still plays through the laptop speaker and nothing plays in the headsets i have just upgrade my laptop to vista and i bought my laptop in jan. Running xp without any problems like this. I have used three different headsets, i have also restated the computer a few times already. Also i have at the top of my keyboard a mute button that when pressed should mute and turn amber but has not since upgrade