How old is the iPhone?
I have an iPhone 7 and as long as I unlock phone prior to plugging the USB/Apple cable to computer with Windows 10, and on the Apple iPhone it asks for allowing access and I select allow, it automatically adds the driver to access the phone then I can access the pictures through the Windows PC at Apple iPhone -> Internal Storage-> DCIM
If you don't get the prompt at the iPhone when connecting the phone to PC try a different cable as maybe the cable is able to charge but the USB data line for D+ and D- is faulty.
Other thing is to verify that the connection is clean to the phone so your getting the D+ and D- for communications over USB.