When trying to resolve issues on an iPhone sometimes "factory resetting" the device can restore functionality. Also, when returning a device or preparing for resale it is necessary to do a factory reset to remove personal information.
Factory Reset Apple iPhone:
1. Tap Settings > General > Reset
- Then tap Erase All Content and Settings.
2. If asked, enter your passcode or Apple ID password
- Then confirm that you want to erase your device.
3. Wait for your device to erase
Depending on your device, it can take a few minutes to completely erase your data.