In my experience this is often caused by the Window's registry. It records USB-connected devices and, after a time, fails to recognise a device's capabilities, even if it has been connected many times before.
The most effective way I know of resolving this is to use Nir Sofer's
USBDeview.
Try this:
1. Disconnect your
iPhone from your PC.
2. Download/unzip
USBDeview (make sure that you choose correctly between x32/x64 versions) then
right-click on the
USBDeview executable and choose
Run as administrator.
3. Sort on the
Description column then select all entries beginning with
Apple.
4.
Right-click on the selected entries and choose
Uninstall Selected Devices.
This will uninstall the
Apple device drivers and - more importantly - cause your PC to 'forget' which USB port/hub your iPhone was connected to and the iPhone's capabilities. (Even better would be to remove the history of all unattached USB devices - but let's not go there... yet.)
5. Re-boot (so your PC re-reads the 'local machine' registry hive in full).
6. Connect your
iPhone.
Whilst it may take several minutes, Windows will enumerate the new hardware connection and go out looking for the drivers (supplied by the installation of
iTunes) and, more importantly, the driver's ability to run
iTunes automatically when your
iPhone is connected (which I believe is a hidden
AutoPlay setting that does
not show in
Settings > Devices > AutoPlay).
PS - @
Bastet makes a good point. In theory there
shouldn't be any difference between the Windows Store version and the version obtained directly from Apple... but I believe there are. In practise I've had more success resolving iPhone/iTunes issues with the Apple version than with the Apple-via-Microsoft version.
Hope this helps...