How to connect iPhone 4s to iTunes?

Before i sign in to my computer and my iPhone is plugged in, it will begin charging. However, when I sign in, it will stop charging, but my computer still recognizes something is plugged in.iTunes is never brought up so i manually open it. No iPhone is recognized so it won't sync. How can I fix this? I have tried different USB cords so I know it is not the cord.

Added (1). Oh and forgot to add. I have checked (definitely have the latest version of iTunes) and tried two other USB ports. Reboot was also done.

Make sure that you have the latest iTune version, reboot your computer (must be Windows) and use another USB port.iTune should recognize it now.