What happened to my flashlight on my phone

Open the Settings App, then go to System → Gestures → Quick Tap. Turn on the feature by pressing the Use Quick Tap button. Scroll down, then tap the Toggle flashlight option. Double-tap the back of your phone to make sure you see the Quick Tap detected notification.

If your flashlight icon is missing from the Control Center, you will need to re-enable the flashlight icon in the Control Center menu of the Settings app. To get your missing flashlight icon back: Open the Settings app, then tap Control Center. Scroll down to Flashlight and tap the green circle.

This may be simply because your device doesn't have enough battery power left to support the feature at that moment. Therefore, you should plug your iPhone into a power source and start charging it. The flashlight feature should start working again once your iPhone has sufficient power.

To use the flashlight, open the Quick settings panel by swiping down from the top of the screen using two fingers. Next, tap the Flashlight icon to turn the light on or off. Depending on your setup, you may need to swipe left to see the Flashlight icon.