IPhone 4 won't play sound through speaker?

My iPhone 4 isn't making any sound through the speakers. There's no headphones in and there's nothing wrong with the jack because the ringer is working completely fine but I can't get any sound to play like music or videos or anything on the internet. I've tried hard resetting it and it didn't work so what do I do?

Weird, if your ringer is still working it rules out speaker damage, when your turn your volume up or down does the volume level on the screen say 'headphones' below? If so it probably has some dirt in the 3.5mm port that is making your phone think something is inserted thus directing all sound data to there rather than the onbaord speakers so trying to clean it with a cotton bud/ q-tip might dislodge the dirt and clear the contacts, if not however your best bet is to just restore the iPhone software via iTunes on your computer, if neither of these worked than a trip to an Apple store will more than likely clarify the problem although if it is a hardware issue Apple don't like to fix their products and will just try to sell you another one at a discounted price when not in warranty

Hope this helps!

I assume you have common knowledge, but I'll just remind you in case you forget (as we all forget things sometimes).
*Go into your settings and go to Sounds. Make sure the option, "change with buttons" is on.
*Make sure you have your volume turned up in whatever app you're using as well as on the home screen.
*Try turning the ringer button to on as well, but I don't believe this should affect the volume.
*Get rid of all of the apps on your recent apps and then try opening a new app.
*Then try turning off your iPhone and turning it back on. This often fixes random little problems for whatever reason.

I assume you're using iOS7, but if not you should find similar results with these steps. If none of the above works, go ahead and look at your speaker. Is it physically damaged in any way? Is your phone new, or is this a recent issue?