Hello, and welcome to JustAnswer.com!My name is XXXXX XXXXX X'X here to help.You'll need to put the phone into Force Restore mode to get it working again:1. Hold the Home and Sleep buttons together until the phone shuts off.2. Release the Sleep button, but continue holding the Home button.3. Plug the phone into your computer and wait for it to show up in iTunes.4. It should appear and say that it's found an iPhone in recovery mode and needs to restore it.5. Restore the phone.That should do it. If what I recommended doesn't help, or if you have additional questions, please let me know and we can continue troubleshooting.