Q: My external speaker stopped working on my Iphone 5. my internal speaker works fine. Is it a setting or has my external speaker gone on the fritz??

Hi Wilson. Try the basic 3 R's. Restart, Reset, Restore. If having to Restore the phone via iTunes, make sure you've created either an iCloud or iTunes backup. Also, if restoring, do not restore from that backup, rather Set Up As New device to rule out any issues with the software contained in the backup. IF this does not resolve your issue, it is isolated to the hardware of the iPhone needing repair.

First, try to reset the phone by holding the sleep and home button for about 10sec, until the Appel logo comes back again. You will not lose data by resetting, but it can cure some glitches. If this does not help, the phone might be stuck in headset mode. Make sure the headphone port is free of any debris or lint, then plug the headphone plug in and out a couple of times.

When you use the volume buttons to toggle the volume, you should see the icon labeled "speaker" and not "headphones" when there are no headphones attached.

More tips can be found here:

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

You're welcome, I'm sure that the Genius Bar will come up with a solution for your problem