Troubleshoot an Apple iPhone 5 by performing a hard reset, resetting all settings, resetting the home button and reopening applications. Applying the methods in the order of generic to specific helps you pinpoint the exact issue. Generic methods cover a greater variety of functions, and feature-specific methods are more likely to repair the phone when you know the component that is malfunctioning.
Performing a hard reset wipes out all data on the RAM. As the RAM does not contain any personal data, a hard reset is completely safe. Likewise, all your settings are in the internal storage, and a hard reset does not affect them. To perform a hard reset, hold down the Power and Home buttons until you see the Apple logo appear on the screen.
Resetting all settings may help. To do so, open the Settings application, navigate to the General section, tap Reset, and then tap Reset All Settings.
You can also reset the Home button. To do so, on an application by Apple, such as Weather App, hold down the Power button until the Slide To Power Off screen appears, and then release the button. Press and hold the Home button until the application closes.
If an individual application is causing issues, try reopening it. Double tap the Home button, hold the application's icon, and slide it upwards. Press Home again, and reopen the application to see how it performs.