I had similar problem, turned out it was the USB cable. I have 2, one connected to PC and one for charging. Somehow they got swapped over and although by then I had uninstalled /reinstalled itunes it wasn't until I plugged the cable in to charge my ipod Touch that I realized that it was not working.
Or try this.
1. Uninstalled iTunes and apple mobile device service completely.
2. Restart the computer.
3. Download and install (or reinstall) the latest version of iTunes. When you install iTunes, you also install the AMDS.
4. Restart the computer.
5. Start iTunes and connect your iPhone or iPod touch. Windows should recognize the device correctly.
To uninstall itunes correctly:click here