There are some simple tricks which are very handy when iPhone 4 speaker doesn’t work. Play the music on your phone, and plug in and out your headphones for a couple of times. Most of the time, this solution is the winner, because the problem often lies in the jack sensor, which may be stuck.
To restart your iPhone 4, press and hold the power button for a few seconds, and slide to power off. When the phone is turned back on, call someone, and check out the speakerphone. It may work perfectly.
Call someone, but during the phone call, turn on the speakerphone. The speaker may start working normally.
Maybe this will help:
- Go to Settings
- Reset all Settings
When the phone is not damaged, the software may be the problem. Make sure to update iOS. You can do it via iTunes or wirelessly, it is entirely up to you.