When I connect my Droid Turbo 2 to my Windows 7 Computer via a USB cable, I can't see any files, photos or videos to transfer to my PC.
I have updated my drivers.
I used to be able to do this by just connecting my old phone - no more
You probably need to switch the phone into Media Transfer Protocol. You can normally do this by swiping down from the top of the screen to pull down your notification curtain. You should have a bar there that says it's in USB Charging mode. Tap there, and change it to media/file transfer mode.