1. If an app is not responding, try restarting the device. If the device is not responding at all, hold the Power/Lock key until the screen turns off.
   
2. If the device does not ring for notifications, try adjusting the volume. If that doesn't work, tap the Settings icon.
   
3. Adjust the desired volume setting.
   
4. If the device cannot receive wireless signals, ensure that Airplane mode is not enabled.