If you hear sound through your iPhone's speaker but not through your headphones, you may have a problem with the headphones, your iPhone settings or its jack. You may not hear anything at all when you plug in your headphones, or you may hear muted or crackly sounds. Try a few settings and jack fixes to try to solve the problem.
Check Your Headphones
Remove your headphones from the iPhone. Check the connector for dirt or dust and wipe it clean with a dry cloth before plugging the headphones back in again. If you hear some sound, but it is muted or crackly, the headphones may not be fully inserted into the jack. Push the connector in firmly until it snaps in place.
If you have a spare set of headphones or earbuds, plug them in to the iPhone. If they work, the original headset may be faulty. If they don't work either, troubleshoot the iPhone's settings and headphone jack.
Check Volume Settings
Look at the Ring/Silent switch on the side of the iPhone. If this switch is on, you won't have any volume. If you can see an orange bar, the setting is on; flip the switch to turn it off.
Check the sound levels by pressing one of the volume buttons on the side of the iPhone. If the bars on the Ringer screen are low, you may not be able to hear through your headphones. Press the Volume Up button to increase the volume to full to see if that solves the problem.
Clean the Headphone Jack
If troubleshooting settings hasn't fixed the problem, check the headphone jack to see if it needs cleaning. Hold it under a lamp or shine a flashlight on it. If you can see lint, dust or dirt, clean it out. Blow in the jack to dislodge surface dust. Use a plastic toothpick or a paperclip with one end opened out to gently pull out any debris that may be stuck at the bottom and sides of the jack. Blow in it again to get rid of any residual dust.
Reset the iPhone
Minor glitches on an iPhone may cause volume problems. A restart clears the system and may get rid of glitches, so turn your iPhone off and restart it to see if this fixes the problem. Hold down the iPhone's Sleep/Wake button until you see the Slide to Power Off slider. Swipe this to shut down the handset. Press the button again to restart the iPhone.
Get Support From Apple
If you can't troubleshoot the headphone jack problem, contact Apple Support. Before you do, play a music track or open an app with sounds to double-check that the iPhone's speakers work. This helps pinpoint whether the jack is the problem or whether you have a another type of sound fault.