My Windows 7 Lenovo laptop won't detect my iPhone 4S but it will charge it?
Normally that would be a question for our friends at Microsoft, but lets try to help you here.

Charging using USB is a dumb function!, so do not pay to much attention to that. 

The question is, 

Do you have the right driver in your Win7 for the ihone? 

How to do that can be read here:

iOS: Device not recognized in iTunes for Windows

Symptoms

Your iPhone, iPad, or iPod touch may not appear under Devices in iTunes after you connect it to your Windows PC.