The iPhone does not appear in iTunes

1- Update your itunes :

Make sure you have the latest version of iTunes. To check for updates iTunes updates are available for Mac, go to iTunes> Check for updates. In Windows, go to Help> Check for updates.

To install iTunes, your computer must be running one of the following operating systems:

     Mac: Mac OS X version 10.6 or later
     PC: Microsoft Windows 7, Windows Vista or Windows XP

     Note: If you use 64-bit version of Windows 7, be sure to download the 64-bit version of iTunes.

2- Reboot your iphone :

To restart iPhone, first turn it off by holding the Power / Sleep button down until you see a red cursor. Slide your finger across the surface of the slider: Your iPhone will turn off after a few moments.

Then restart your iPhone by holding the Power / Standby button pressed until the Apple logo appears.

The iPhone does not respond? To reset the iPhone, simultaneously hold down both the Sleep / Wake button and the Home button for at least ten seconds, until the Apple logo appears.

If your device does not turn on, or if a red battery icon appears, try reloading.

3- Check the USB connection :

Try disconnecting and reconnecting the iPhone.

Whenever possible, connect your iPhone to a USB port built into the computer and not into a USB port on a keyboard or an external USB hub.

If the iPhone still does not appear in iTunes, try another USB port.

4- Conflicts with software :
    
Some third party software (such as security software and antivirus software) may prevent iTunes to recognize your iPhone. You may need to update or disable your software, or to change their settings.