This article will show you how to get the alarms on your iPhone working again.
Why Your iPhone Alarm Won't Go Off
This may sound obvious, but don’t skip this step. It is possible to increase the volume using the buttons on the side of your phone without increasing the alarm volume. This is because the iPhone allows you to control two completely different sets of sounds with the same buttons.
For example, if you have a music streaming app open, you can use the buttons to control the music volume instead of the alarm volume. If the alarm volume is turned down or off (even if the music volume is turned up), you have a silent alarm.
Go to Settings > Sounds or Settings > Sounds & Haptics and make sure the RINGERS & ALERTS slider is set to a reasonable volume. There's also the Change with buttons option here, which you should turn off to ensure that your ringer and alarm volume never changes when you change the system volume with the buttons.
