What if my ringer button is not working? How will I keep my mobile in silent mode?

Mute switch not working: It might be just dirty (have your device inspected at an Apple Store or AASP)

Alternatively, use DND as per these instructions:--> Use Do Not Disturb on your iPhone, iPad, and iPod touch - Apple Support

Regards

Giulio

There are two ways to turn Do Not Disturb on or off: Go to Settings > Do Not Disturb to turn on ...

Use Do Not Disturb on your iPhone, iPad, and iPod touch