Losing the data from your iPhone can happen for lots of reasons, including:
- Repairs that require you to erase all data on phone
- You may have erased the data (by accident or on purpose)
- File corruption.
And while losing your iPhone’s data is never a pleasant experience, restoring iPhone data from a backup is a fairly simple task that can have you up and running again in no time.
Each time your sync your iPhone, the data, settings, and other information on the phone are automatically backed up on your computer. If you encounter a situation in which you need to restore, though, all you need to do is download this back up to your phone and you’ll be off and running again.
To begin to restore your iPhone data from the backup, connect your iPhone to the computer that you normally sync it to that contains the backup file (in most cases, this will be your normal computer. If you’re syncing to more than one machine, you should have backups on both computers. Just choose the computer with the backup you prefer).
In the center of the iPhone management screen, you'll see a "Restore" button. Click that.
When you do this, iTunes will show you a few introductory screens. After them, you’ll need to agree to the standard iPhone software license. Do so and click Continue.