How do you restore an iPhone?

To restore your iPhone from a backup, you should:

1. Turn on your device. You should see a Hello screen.
2. Follow the onscreen setup steps until you reach the Apps & Data screen, then tap Restore from iCloud Backup. 
3. Sign in to iCloud with your Apple ID.
4. Choose a backup. Look at the date and size of each backup and pick the most relevant one. After you've chosen a backup, the transfer will start. If a message states that a newer version of the software is required, follow the onscreen steps to update.
5. When asked, sign in with your Apple ID to restore your apps and purchases. If you've purchased iTunes or App Store content using multiple Apple IDs, you'll be asked to sign in to each. If you can't remember your password, you can tap Skip this Step and sign in later. You won't be able to use the apps until you've signed in with your Apple ID.
6. Stay connected to Wi-Fi and wait for a progress bar to appear and finish loading. Depending on the size of the backup and the network speed, it may take anything from a few minutes to an hour for the progress bar to be completed.
7. Now you can finish the setup process and enjoy using your device.