iPhone 3G: Why won't my Speakers Work?

My speakers on my iPhone 3G won't work at all, I can't here music through them, here my ringtone, or put phone calls on the speaker, but I can here everything when the headphones are plugged in. I have tried almost everything i restored my settings, and tried that one soution that says that there are headphones plugged in to the phone, when there really isn't, but my iPhone still doesn't work. Please Help.