Restoring an iPhone wipes off all of the files, preferences and apps and installs a brand-new version of the operating system. If you fail to complete a full system backup before you restore your iPhone, you will need to download all of your apps and files again. With a backup, you can save a considerable amount of time and frustration.

Creating a Backup

To protect your app data, back up your phone before restoring it. Depending on the generation of your iPhone and the iOS version you are using, you can create a backup to iTunes, iCloud, or both. To automatically back up your phone to your iCloud account, go to "Settings | iCloud | Backup & Storage" and turn the "iCloud Backup" slider to "On." If you prefer to use iTunes, choose "Devices" from the "File" menu and choose "Back up."

Restoring from a Backup

Once you have completed a backup, you can go about restoring your phone. As you are setting up the new operating system, the Setup Assistant will give you the option to "Set Up as New iPhone," "Restore from iCloud Backup" or "Restore from iTunes Backup." To restore your apps, choose the iCloud or iTunes option.