Retore Boot Camp back up plist

I have attempted to modify the Boot Camp Assistant plist (via Terminal) as shown on the web and in discussions on this site to allow my old MB Pro (13 inch, late 2011) install Windows 10 from a USB. My MB has an optical drive and won't find the USB. I am also running OS X Yosemite 10.10.5.

In short, I was unsuccessful. The best repair I have been able to do is get Boot Camp to load and stop responding. That has been by manually changing back the original changes I made.

I have even tried to delete and replace Boot Camp Assistant with a back up of all the apps that I have. However, the OS won't let that happen. It will not delete the app, nor allow it to be modified with a drag and drop of the same app in the hope it will update itself back to the original.

Before I made the changes, I followed the instructions to make a back up of the original plist. Does anyone know how and where I can find it? Once I've found, how do I restore the original plist settings to Boot Camp so it works again?

Thanks in advance.