How to Load Your iPhone’s Backup
Sooner or later the backup you created using iCloud or iTunes might come in handy. You may have to erase and reset your iPhone because it's gone haywire or maybe you had to send your iPhone in for repairs. The best case scenario is you got a new iPhone and want to restore your old data to your new phone.
To load the backup file onto your iPhone, old or new, from iCloud:
Tap Erase All Content and Settings.
When the Setup Assistant opens, tap Restore from iCloud Backup.
Sign in to iCloud with your Apple ID and password.
iCloud pushes the most recent backup to your iPhone.
If your backup is on your computer, and you use iTunes to restore the backup to your iPhone:
Connect your iPhone to the computer you usually use to sync.
Open iTunes, if it didn't automatically open (depends on how you set it up).
Click iPhone, or whatever you named it, in the devices pop-up menu in the upper right.
Click the Summary tab.
Click Restore Backup.
iTunes gives you a chance to back out of your choice or go ahead. Clicking Restore iPhone will erase your iPhone and re-install the most up-to-date operating system.
You then must restore from a backup or start over with your iPhone. Choosing to set up as a new iPhone is a good option if you plan to give your iPhone to someone else and want it to have a clean slate.
If you see multiple backup files, choose the most recent one associated with your iPhone.
Sync your music, videos, podcasts, and books.
Tap Settings→iCloud and sign in to your iCloud account to sync your Contacts, Calendar, Notes, bookmarks, and all the other data that iCloud manages.