Q: phone has no sound will only play with headphones

Did you already reset the phone by holding the sleep and home button for about 10sec, until the Apple logo comes back again? You will not lose data by resetting.

If you toggle the volume up and down, without the headphones attached, does the icon on the screen is labeled  "speaker"?

If it still says "headphones", your phone is stuck in headphone mode. Check the headphone port for any kind of debris or lint and plug the headphone jack in an out a couple of times.

Also check this article for more troubleshooting tips:

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

Anything paired to your Bluetooth settings?

same for me, iPhone 6s new today, works for a few newly paired BT devices, headphones on a cable work, no sound at all from the iphone speaker.

Not even a section in the menu for iPhone, just the bluetooth devices and headphones are listed

tried resetting, rebooting, still searching set up menu's

Sorry, there is no section for sound being played from the speaker.

Did you check if the speaker is working if you get a call, for example?

If there are any bluetooth devices like headsets or bluetooth speakers still paired to the phone, there will be no sound from the external, built in speaker.

no sound from the iPhone being used as a phone, the small speaker we use to listen to a conversation, there isn;t an iPhone selection..

bluetooth devices work for calls, videos, music, which cut out the iPhone "speaker"

the speaker works for calls, not for web sites (you tube) or music or videos playing on the iphone

all airplay device work for audio / video if selected

Maybe the phone doesn't have a personal speaker, there isn't even a SW selection choice in any of my menu's for iPhone just the airplay devices, the bluetooth devices I paired and headphones....

Before you start your own thread, did you check if the volume bar is moving up an down if you play a video in youtube, for example?

Underneath the speaker icon, that comes up on the screen as soon as you toggle the volume up or down, you should see the word "Speaker" and not "Headphones" or "Ringer volume"

The iPhone remembers the volume selection for certain apps or devices.

To make sure that this is not software related, set it back to factory settings, without using any backup data afterwards. Set up the rest of the personal settings manually and test the speaker.

If the speaker works, restore from the latest backup. If the problem comes back, the backup data contained corrupt data, causing your issues.

If it still does not work, this could be  a hardware issue and the phone has to be checked by Apple or an Authorized Apple Service Provider:

Use iTunes to restore your iOS device to factory settings - Apple Support

Find an Apple Authorized Service Provider

iPhone - Contact Support - Apple Support

Also check the settings for Settings/Music/Volume limit, to make sure it is set to maximum.