In most cases, you can solve these problems by putting the phone into recovery mode and restoring it from backup. To do that, follow these instructions: 1. Connect the iPhone's USB cable to your computer, but not your iPhone. 2. Turn your iPhone off. If the phone won't turn off in the traditional manner, just keep holding the buttons until the screen goes dark. 3. Once you've turned the device off, press the home button on the face of the device and plug in the USB cable to the device's dock connector. 4. When it turns on, keep pressing the home button until the iTunes logo appears on the screen. 5. You'll know the phone is now in recovery mode because a window in iTunes will tell you. 6. You can then start the restore process by clicking the "Restore" button in the iTunes window.