If it used to work, I'd do a system restore back to when it still worked. Still, it's possible it's a hardware issue.
i have a dell inspiron e1505 laptop. i turned it on the other day to watch a movie and my volume button was not working. i clicked volume up and down and the mute button, and nothing worked. i clicked the control panel and under the sound and audio device it showed nothing being played. it says no audio device. i cannot manually move up or down the volume. it just has nothing there. i am computer illiterate and could use some help.