Q: iphone5 doesn't ring when locked

Hi mehdi.gh, 

Thank you for using the Apple Support Communities!

I understand that your iPhone is not ringing when it is locked. I see that you have already tried some great troubleshooting as well. 

To continue troubleshooting, I suggest reading over and working through the information in the following article. Some of these steps you have already completed, but for the sake of completeness, I suggest working through all of the steps. 

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

Cheers!

Thank you for responding and letting us know that the issue remains. 

To continue troubleshooting, I would first like to make sure that your iPhone’s operating system (iOS) is fully up to date. 

Update the iOS software on your iPhone, iPad, or iPod touch - Apple Support

When someone calls your iPhone, does it vibrate? Are you able to see on the display that someone is calling? 

Have a great day!