I had the same problem and found the answer on one of the Apple forums. This is a recent issue for those who work with 64-bit Windows and have updated iTunes to the latest version 12.1.
This version of iTunes replaces 32-bit support for the Apple Mobile Device with a 64-bit version that iPCU does not support, since it is 32-bit.
Solution Method:
- Remove Apple Mobile Device support and Apple App support through the Windows Control Panel.
- Download the iPhone setup and extraction utility using 7-zip
- Install AppleApplicationSupport.msi and AppleMobileDeviceSupport64.msi (not against 64, it's just an installer that is 64-bit, 32-bit binaries)
Screenshot for your confidence 
Note. If you still need to use iTunes, you will have to use version 12.01 until Apple's lazy asses fix it.
Edit: Apparently, they are not lazy, but selfish injections. iPCU no longer exists. It has been replaced by Apple Configurator, which was not released for Windows.
Mike
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