PLEASE HELP<< Unplayable World?

I was using Minecraft 1.12.2, and made a command block to kill @e within 2 blocks- /kill @e[r=2]. It worked fine and would do exactly what it was supposed to do. But when I changed the value to r=1.5, it started instakilling me in an endless loop, even though my spawnpoint was much farther than 1.5 blocks away. I decided to switch to 1.14 because I knew the commands were reformatted. I figured I could switch to 1.14, destroy that one command block, then return to 1.12. I not sure if this is relevant, but when I switched to 1.14, the command block was indestructible even though I was in creative and also commands wouldn't work, so I went back to 1.12, only to find my entire world corrupted and everything deleted!?! PLEASE HELP! (I did make a backup, but not sure how to apply it< Folder is attached).