Some people reported some issues with the iPhone, such as freezing or not responding properly. So, the best thing to do to solve these issues is to hard reset your iPhone, or restore it to its default settings.

To hard reset the iPhone follow these few steps, this image also will help you figure out what I will be talking about.

1. Press the home button – the big circle below your screen- and the sleep button located on the top of the iPhone simultaneously.
2. Keep pressing for at least 15 seconds; you should see the color fading to black.
3. Wait couple of second and press on the wake/sleep button again.
   Your iPhone should turn on.

iTunes also can help you reset and restore the softwares and return it to its original state. But keep in mind that if you restore your iPhone to its original state you will lose all the data you saved including videos, images, music etcc.

Here is how to restore the iPhone to its original state.

1. You need an internet connection, and also need the latest version of iTunes software installed on your computer.
2. Connect your iPhone to your computer.
3. Click on iPhone in the Source pane and click the Summary tab in iTune.
   Check for updates to update your software or you can go ahead and choose Restor, to restore to its original settings.
4. Follow the screen to guide through all the steps.

If you just want to reset the iPhone to its original preference; without deleting everything on it, Choose General > Reset and tap Reset All Settings.

To reset Network Settings, Choose General > Reset and tap Reset Network Settings.