Charge your iPhone
If your iPhone's battery is almost empty, the flashlight may not work. This is all the more true if the phone is very warm or very cold, conditions that already reduce its proper function. Charge your iPhone, get it down to a moderate temperature, and try again.
Close the Camera app
If your phone's camera app is open, the flashlight won't be able to take control of the LED.
- On an iPhone X or later, swipe up and hold on the center of the screen, then swipe up to close the Camera app.
- On an iPhone 8 or earlier, tap the home button twice then swipe up to close the Camera app.
Reset your iPhone settings
If a basic restart doesn't do it, reset your phone's settings. You won't lose any data, images, or other stuff, but you may need to reset your wallpaper and alarms and other basics.
1. Launch the "Settings" app, then tap "General."
2. Then tap "Reset," and finally "Reset All Settings."
3. Tap "Confirm."
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