Is there a way to access all the system files on my windows phone 8.1?

I have a Nokia Lumia 920 running windows phone 8.1.

I remember reading a post long time ago, illustrating, how to access all system and hidden files (app data etc) on windows phone 8.1 by connecting the phone to a windows PC via USB, and running some software. Not able to find that post now..

Anyone tried this? Please help me, need to back up some important data.

Thanks a bunch.

I recall a similar post. I believe it was only for WindowsCE and maybe even WP7, but not WP8.