Step-by-step Guides to Locate/Update iPhone 4 USB Driver for Windows 7:
Connect your iPhone 4 to the computer with Windows 7.
Quit iTunes if it launches.
Click and open Device Manager.
Click the disclosure triangle next to Universal Serial Bus controllers to expand this selection.
Please note: If you do not see "Apple Mobile Device USB Driver" listed, follow these steps:
Disconnect iPhone 4 from the Windows 7 computer.
Take a photo with the iPhone, save a screenshot by pressing the Home button and Wake/Sleep buttons and letting go. The screen should flash briefly.
Open the Device Manager in Windows: Click Start, in the dialog, type devmgmt.msc and press Return on the keyboard. If Windows needs your permission to continue, click "Continue".
Expand the sections labeled, ot all sections may be listed:
Universal Serial Bus Controllers
Look for the entry that recognizes the device as a camera. This entry should be called Apple iPhone.
Look for any other entry that represents the device. If you see Apple Mobile Device USB Driver, Unknown Device, or any name for your device other than the camera entry.
Locate the Apple Mobile Device USB Driver in this list. In some cases, you may not see this, but will find "Unknown" in its name. In other cases, Apple Mobile Device may be located in a different section of the Device Manager, such as "Other Devices".
Optionally to update the Apple Mobile Device USB driver, right click the Apple Mobile Device entry in Device Manager and choose Update Driver Software.
Select "Browse my computer for driver software".
Select "Let me pick from a list of device drivers on my computer".
Click the Have Disk button. Note: If the Have Disk option is not present, choose a device category such as Mobile Phone or Storage Device if listed, and click next. Then the Have Disk button should appear.
Click the Browse button, then navigate to the following location: C:\Program Files\Common Files\Apple\Mobile Device Support\Drivers.
Note: If using a 64-bit version of Windows 7, navigate to C:\Program Files (x86)\Common Files\Apple\Mobile Device Support\Drivers.
Double-click the usbaapl file. (This file will be called usbaapl64 if you have a 64-bit version of Windows 7)
Click OK on the Have Disk window. Then click Next-> Finish. Windows installs the USB driver.
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