If your device keeps shutting off without apparent reason, or if it is functioning in strange ways, your device settings may have become corrupted. You'll need to restore them to the original settings. This will not erase your contacts or calendar data, or delete any music or videos that you have downloaded to the device. Here's how to do it:
- Open Settings> General> Reset.
- Tap on the Reset All Settings button.
- When asked to confirm, tap on Reset.
If your iPhone is still not working correctly, you can try erasing all the content on your device. Open Settings> General> Reset and tap on the Erase All Content and Settings button. After doing this, you will have to restore your data using iTunes. For more on this, see next column.