I got it to work for me after 2 days of trying stuff out.
I'm running windows7 and my S4 is on version 4.4.2
First with S4 and USB cable that came with phone for charging, I connected together with PC.
It would not read MTP device properly.
I searched for the "device manager" on my pc, I went to the "start menu", went to "computer", then in that window went to "system properties", then located "device manager", another window opens and should give a list of items that copile as part of the PC, in "portable devices" it was showing me that my device was a "code 10" with a little yellow yield sign, clicked on it and another window opened, clicked on "driver" tab and I uninstalled the driver while still phone was still connected. I restarted my phone with cable still connected.
I then restarted my pc with phone still attached. once PC got to the desktop page I disconnected phone from cable while cable still attached to pc and reattached cable at phone (had a small quote box in bottom right saying it was installing device driver). Then a small window popped up giving me my "device options"
hope this helps someone out there.