How can I restore my iPhone with iTunes when it boots to a black screen?

If your iPhone fails to boot up repeatedly you may have to restore it with iTunes and your computer. To restore the iPhone completely follow these steps:

1. Before you connect your iPhone with the USB cable, start iTunes. Make sure iTunes is finished downloading podcasts, updating, etc.
2. Connect your iPhone to the computer and wait 10-15 seconds for the connection.
3. Press and hold both the sleep/wake button and home button on your iPhone.
4. After 10 seconds, release the sleep/wake button and continue to hold the home button only.
5. Wait a few more seconds and iTunes should pop up a dialogue box that asks if you are ready to restore your iPhone. Your iPhone is in recovery mode.
6. Follow the steps in iTunes to restore.

Sometimes when you press the home button and sleep/wake button together the iPhone will try to reboot again. If this happens and you see the Apple logo disconnect the iPhone and start from step 1.

After restoring your iPhone OS you can sync your contacts and music, or even restore from a backup (as long as you've synced your iPhone and made a backup previously on the same computer).