Periodically I move pics from my phone to my computer.  The USB icon doesn’t always appear asking if I want to charge or move files.  What works is swap out to a new cable or do the Developer Options below.  Then don ‘t do it on my phone, go to my desktop and access the phone from there.

Connect phone and computer
Open the cover at the bottom of your phone.
Connect the data cable to the socket and to your computer’s USB port.
Select USB connection setting (One does not appear.)

Slide your finger down the display starting from the top edge of your phone.
Press Connected as a media device.
Press Media device (MTP) until the function is turned on.

Go to Settings › Storage › again settings (on action bar). There should be “USB Computer connection” option. (THERE IS NOT.)

Tap on it and choose “mtp mode”. That should make your phone visible to your pc.

THAT DIDN’T WORK FOR ME BUT HERE IS WHAT DID WORK  

Apps > Settings > Developer options > (Scroll down to the Networking section) > USB configuration > (select MTP  (Media Transfer Protocol)).

You will get a pop up on your phone that says: “Allow access to phone data. An MTP connection will be established to access the data on the connected device.” Just hit Allow.

After doing this I got a pop up on my desktop for the usual options of a media device and this time when I clicked on “Open device to view files” it actually worked. I was able to access sound clips, videos, photos, you name it. (I could not get the USB Confirguration to change from “charging” and Windows gives me the error msg that the device is not recognized. I kept trying different cables and one worked.) If you don’t get the msg, go to your desktop file explorer and with the right cable you will see it there

Another thing to note is after I disconnected my phone from the computer and tried again I had to go through the menus again and set it from Charging to MTP.

Also, if you don’t have Developer options go to: Apps > Settings > About phone > (tap on Build Number several times until it unlocks the Developer options). Now the Developer options should be right above About phone.