HELP! MY WORLDS BROKEN AND I DON'T HAVE A BACK-UP

So I had enrolled previously to the Xbox insiders program, but I recently quit the program beta, but... It was still there after I quit the program. So I uninstalled and reinstalled Minecraft, but now, my world I have spent 2 YEARS on is completely broken. the are chunks of my world that I spent hard work on that are gone. this really devastated me as I really worked hard on this.

but what's worse is, I don't have a back-up! (unless the back-up is the world on the legacy edition of minecraft) but if not, I don't know what to do, the legacy edition of my world has nearly an entire year of work that isn't on it. this is a complete disaster.

SOMEONE PLEASE HELP!!!