my world is bugged or something like that

I had dogs in my world and animals and more and in a message he told me that they had been suffocated by the walls, I have nothing in the chests and I had many things, there is a big crack in the world, I had paintings with diamonds and now only There are the paintings and a bandit painting and it is black, the beds were white and now they are red and among others.
I think I was the one with the error and now I don't know how to solve it because I deleted from the world a file called “level.dat and level.dat_old, I really would like your help, the truth is that I would not want to lose this world I have many things🥺.