Q: no volume on iphone 4 unless head  phones plugged in

Hi torquey1,

So it sounds as if you are not getting any sound from your iPhone unless you use headphones plugged into the jack, is that correct?

I would suggest that you troubleshoot using the steps in this article - 

If you hear no sound or distorted sound from your iPhone, iPad, or iPod touch speaker - Apple Support

Thanks for using Apple Support Communities.

Sincerely,

Brett L