The iPhone is a popular smartphone created by Apple that doubles as an iPod. It can hold music, videos and even books. If you have lost the accompanying files on your personal computer, your iPhone will be unable to sync. In an effort to stop users from stealing content off of other iPhones, Apple's iTunes does not allow the transfer of files from the iPhone to iTunes. However, there are third-party programs available which can help transfer your iPhone's files back into iTunes and restore your media collection.
Download and install onto your computer an application that will allow you to rip the files from your iPhone (see Resources).
Connect your iPhone to your computer by inserting the iPhone USB cable into the device's dock connection and an open USB port on your computer.
Launch the iPhone ripping software on your computer. The software will guide you through the remainder of the process to transfer the files currently on the iPhone directly to iTunes (it's often as simple as clicking a single button).