I HAVE FIGURED IT OUT!
I lost my world called Grand View City after my internet died. I saved and leftthe game after being disconnected from Xbox live. I restarted my PC and I logged back into Minecraft Bedrock. I then noticed that my City was gone.
After many attempts I figured out a way to get my old deleted/ corrupted worlds that
wasn't on my list of worlds to appear.
I created a new world, I made the new world have the same settings as my world that got deleted/ corrupted. I logged into the New World (which is named Grand View City)
and I took the "level.dat" and "level.dat_old" and dragged them to my desktop.
I then got my original Grand View City level.dat and level.dat_old and
dragged them into the New World (The New Grand View City) (I also
took the title.txt from my original level and replaced it with the New Worlds title.txt
Its confusing, but this really consists of just drag, drop and replace.
if anyone needs more help with me explaining this, feel free to text and reply. i could make a vid on this to make it easier. have a good day! :)