No Sound except through headphone jack?

I can hear sound when I wear the headphones or plug in speakers through the headphone jack. It would be best if I could hear it without the headphones.  I'm so frustrated..... Anyone help with my Inspiron 9300 Please. I'm using Windows XP with sp2.

 

This is what has been done....

Checked audio volume in control panel.

Checked program (itunes, PoweDVD....) Volume

Downloaded and reloaded audio driver (Sigmatel C-Major)

 

Any Ideas would be helpful :)

 

Thanks in advance