If you’ve installed iTunes 11.1 (released 2013/09/18), and now iTunes can’t find your iPhone / iPad / other iDevice over USB, this is how to fix it.
NB: None of the below applies if you are syncing over wifi, that should work without doing any of this. It was working for me, but I wanted to force install a .ipsw so needed USB to work.
With your device plugged in, Open Device Manager and see if you have an “Apple Mobile Device USB Driver” under Universal Serial Bus controllers:
I’ve got two on mine because I had both an iPad and iPhone plugged in.
Anyway, if you don’t see those, you need to follow the instructions on how to update the drive on the Apple kb article here: http://support.apple.com/kb/TS1538
Again, in short, navigate to the device in Device Manager under “Portable Devices”, update driver, and point it at the driver in c:\program files\common files\apple\movile device support\drivers , and tell it to use the one it finds.
Unplug and replug your devices and iTunes should pick them up.
Hope this helps someone out. Leave me a comment if it does.