The iPhone is designed to work with iTunes. Basically if you don't use iTunes, your phone is not backed up, unless you use the Gmail app. We have to get your phone talking to iTunes.
The first thing to do is switch out the USB cable, and try a different USB port. The phone is supposed to work without installing a driver. This will fix it most of the time. If not:
1) Click Windows Start/Home button
2) Type "devmgmt.msc" at the search (without quotes) textbox. Or go to device manager from control panel Or Right-Click on My Computer>Properties, Choose "Device Manager" from the left pane..
3) Expand "Universal Serial Bus Controller".
4) While iphone is connected, click the unknown device.
5) Right click the same and click on Update Driver Software
6) Click the second option "Browse my computer for driver software".
7) Click on "Let me pick from a list of device drivers on my computer"
8) Click on "Have Disk" button.
9) Browse to the the path "C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers"
10) Select "usbaapl.inf"
11) Now select "Apple Mobile Device USB Driver" under list of hardware model section.
12) It will add "Apple Mobile Device USB Driver" under "Universal Serial Bus Controller"
13) Restart your computer.