iPhone 4 will not connect to any computer and will not show up in device manager
Lets do some troubleshooting.

Verify that Apple Mobile Device Support is installed on your Windows laptop.

iOS devices require Apple Mobile Device Support, which should be automatically installed with iTunes. To verify whether it is installed, follow the steps appropriate for your Windows operating system. (7)

Click Start.
Choose Control Panel.
Click "Uninstall a program".
Verify that Apple Mobile Device Support is visible in the list of currently installed programs.


If not there, re-install iTunes.