No sound on all apps

Re: "I’ve a iPhone 13 Pro Max : No sound on all apps"

If your phone isn’t working right, try re-starting it: Turn iPhone on or off - Apple Support (deletes temporary files).

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Re: "No sound on all apps"

If they are third-party (non-Apple) apps (eg: Zoom) you may need to permit them to access microphone / speaker

You could check your Privacy / Security settings.

Else:

Wondering if you have turned up enough volume in order to hear ...

Adjust the mono audio, balance, and phone noise cancellation settings on iPhone - Apple Support

or

if you have do not disturb or "silent" mode switched on:

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

or

"When you’re on a phone call, you can switch the audio to the speaker or to a Bluetooth device.

Check if the audio is set to a bluetooth device: While on a call on iPhone - Apple Support

You could try turning off "Low Power" mode if you have it turned on ... see if that helps with sound

Use Low Power Mode to save battery life on your iPhone or iPad - Apple Support

says:

"To turn Low Power Mode on or off, go to Settings > Battery. You can also turn Low Power Mode on and off from Control Center. Go to Settings > Control Center > Customize Controls, then select Low Power Mode to add it to Control Center."

More troubleshooting info:

If the microphones on your iPhone aren't working - Apple Support

Change iPhone sounds and vibrations - Apple Support

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More info. / support / contact:

For a new phone, you can always check with the experts:

One stop for technical support, Apple hardware service, and software support.

Call Apple Support at 1-800-APLCARE (or use the app)

AppleCare Products - Apple

or

iPhone - Official Apple Support