You can easily reset the iPhone, iPad or iPod touch to factory settings if we're having trouble - even if it does not start - and reinstall the entire operating system iOS.
There are several ways to do this, and we will review them from the simplest to the most complex. You only need to have on hand a PC or Mac with iTunes installed to restore the operating system of the device.
Performing a Factory Reset
The factory reset returns the computer to its factory settings and is the quickest and easiest option to run. The device is "like new", because all settings are cleared qwue have done, as well as local applications and data you have downloaded. When finished, it will be necessary to perform the initial setup of the computer again.
Of course all data synced with your iCloud account or another online service will be restored after the device log on with your username and password. If you had configured iCloud will automatically back up all local applications and data will be restored after the device is reset and reinstall your applications.
This type of reset is ideal if you want to leave the device in a "like new" if, for example, going to sell it or give it to someone else.
To make the standard factory reset, just press the icon in the Settings application on the Home screen of the device. Then touch the General Settings category, and Reset search below. We played "Erase All Content and Settings" and we type the PIN when requested. In a modern iPhone or iPad, your device deletes the encryption key that protects access to their data, ensuring that it can not recover and mark the sectors of memory available for use. This will only take a few minutes.
Restore with iTunes
The above process only removes your data and applications. No reinstall the whole OS. So if the system crashes or other problems are experienced, the system files may be damaged. This can be fixed by connecting the device to a PC or Mac with iTunes. iTunes can download the operating system of Apple device and reinstall a new copy on the device, thus replacing the old operating system and really start from scratch. This is known as "restore" (Restore).
First, we must open iTunes on your computer. Make sure you are using the latest version of iTunes for this.
Then connect the iPhone, iPad or iPod Touch to your PC or Mac via USB cable. The USB cable is usually attached to the wall charger - is the same cable used for charging. Unblock the device PIN and press the button Confidence to trust that computer.
Select the device when it appears in iTunes and click on the Restore button. iTunes will restore your device with a clean copy of the iOS operating system, in addition to removing all personal files and other data.
If the device does not boot or restore process in iTunes does not work, then you have to use the recovery mode to repair the device. For this we must have iTunes open on the computer before.
To enter recovery mode, you must first turn off the device completely. Hold down the power button to turn it off and slid. If the device does not respond, you must press and hold down both the power and home buttons at the same time and for a few seconds until it turns off.
Then the USB device cable connects to the computer with iTunes. Hold down the home button until the screen "Connect to iTunes" appears: you will see a connector pointing to iTunes icon. Now you can release the button. If you do not see this screen and the device starts normally, you need to try again until it does. Just make sure you hold the start button until the display shows:
iTunes will then inform you detected a device in recovery mode. We click on the Restore button and iTunes will restore the operating system of the device.
If neither of these methods solves your problem, then your device has some serious hardware problem, and it would be best to take Apple for review.