Ear speaker not working

hardware issue. call apple or go to the apple store and have the device replaced

Try disconnecting the headphones and then adjusting the volume, does it say headphones?

If it does, there might be something in the headphone jack, maybe lint, dirt, or something else in there.

You can try getting it out by connecting the headphones 5-10x or spraying compressed air into the jack.

If it doesn't say headphones or there isn't anything in there, try restarting or restoring the iPhone.