I cant get in my minecraft world

I defeated the Ender Dragon and I was just exploring the end like normal then I left the game like normal and I tried to get in again but it was just stuck in the full loading bar. I tried making a copy of the world so I did and that world didn't work either. Then I saved a file on my hard drive of the world and I uninstalled Minecraft and installed it again and tried importing it again and it didn't work it said the it failed to import the world. Then I had to go to the old version of the world that I luckily saved and defeated the Ender Dragon again right away with nothing just fists and blocks and one pickaxe and it took me forever but I finally beat it again and I went exploring and found an end city and I had to leave Minecraft and I thought it would be fine because so far Minecraft was working fine like on the other worlds and then the next hour I tried getting back in but it didn't work. The other backup file was deleted so I couldn't get in the world at all so now I'm just stuck completely and I cant fix it. I don't know if anyone else has been having this issue but I really hope Mojang can fix this again I really want to play Minecraft again and I dont want anybody to experience the same thing and I hope I don't have to completely start again just to have the same thing happen again.