Backup using ADB without root or usb debugging
You may need to 'upgrade' the driver to the adb version.
Open Device Manager, find your phone and right click it. select "update driver software". On the window that appears choose the "let me pick" option. You should then see a couple of different drivers, select the one that includes "adb" and click ok through any further windows. (remember which one was selected before so you can repeat this to return to the 'normal' driver)
You should then be able to run the adb backup.