iphone 4s is not connected to itunes
Follow these steps, testing to see if the issue is resolved after each section.


Update iTunes
Check the USB cable
Verify that Apple Mobile Device Support is installed
(can be found in installed programs)
Restart the Apple Mobile Device Service
Windows Vista or Windows 7
Close iTunes and disconnect the iPhone, iPad, or iPod touch.
Click the Windows Start button  Start button.
In the Start Search field type Services.
In the Programs section of the search results, Click "Services".
Select Apple Mobile Device and click Stop the service.
Verify that the Apple Mobile Device USB Driver is installed
1.Connect the device to the computer.
2.Quit iTunes if it launches.
For Windows Vista and Windows 7:
3.Click the Start menu, right-click on Computer, and choose Properties.
In the upper-left corner, click Device Manager. The Device Manager window should open.

4.Click the plus (+) icon (or disclosure triangle () (for Windows 7 and Windows 8) next to "Universal Serial Bus controllers" to expand the selection.
5.Locate the Apple Mobile Device USB Driver in this list. If this entry is displayed without any downward arrow, "!" or "?" symbols over it, then this driver is successfully installed.
If the Apple Mobile Device USB Driver is not listed, reinstall it (instructions on apples site)
If the Apple Mobile Device USB Driver entry is listed, but has an exclamation mark or question mark over it, continue to the next steps to reinstall the Apple Mobile Device driver.
Check for third-party software conflicts
Uninstall any cellular device connectivity software from vendors such as Samsung, Nokia, Bora, Novatel, Sony, Android, LG, Sierra, Huawei, Pantech, or Motorola and see if the problem persists.
Reinstall Itunes


For a way more detailed explanation check here:http://support.apple.com/kb/ts1538