Issue in getting back the old firmware

Hi guys,
I have a Black cube with Pixhawk 2.1 with a particular firmware installed on it. I accidentally installed the latest Firmware on it. Now, I want to get it back. Is there any way to do this?
I read that in the SD card inside the Black cube, there are log files. Is it possible to fetch the old firmware from that?
Also, does every company create its own firmware or is it a standard firmware that is available on the internet?