Need to know:
- What type of iPhone?
- What version of iOS?
Try:
Launch iTunes and plug your iPhone into the computer using the USB cable. Click "OK" on the alert window that appears informing you that iTunes has detected an iPhone in recovery mode. Click the name of your iPhone in iTunes. Select the Summary tab and click "Restore iPhone."
**** THIS MAY DELETE CONTENT ON YOUR PHONE - I AM NOT RESPONSIBLE **