Hope these three ways can be of some help.
1. Update Windows, update iTunes and make sure your iPhone is running the latest firmware. Restart your iPhone and PC. And connect your phone using the original Apple USB cable.
2. Make sure your iPhone trusts your computer.
3. Update iPhone drivers. open Control Panel > Hardware and Sound and then look for Apple iPhone under the “Unspecified” section. Right-click on it, choose “Properties” and then click the Hardware tab. Click Properties and then the Change settings button. Click on the Driver tab and Update Driver… and then Browse my computer for driver software. Now navigate to C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers and click Ok, then Next. You’ll either see a message saying that the best driver is already installed, or a new driver will be installed. If the latter, your iPhone should now show up in iTunes.
If you are looking for a better and easier way to connect your Smart Phone to your computer, try using AIR MORE. It’s brilliant, simple scan of the QR code and to register your device and you get started simply.