Hello there. I have a story that may make you think twice about deleting one of your Minecraft worlds.
You see, I am a one-year veteran in the indie game Minecraft. Like most players, I remember my first world on my laptop. It was an interesting map. There was a hill dead in the middle of a standard craftable map.
To the south was a beach which led to an ocean, to the east a vast desert, to the north a natural lava pit, and finally to the west a vast forest. I decided this would be the perfect place to set up base. I dug a square hole in the hill with a glass roof that was level with the top of the hill. This was my level for the summer. Once summer ended and I went into the 8th grade, I slowly forgot about my level.
Around Christmas break, I noticed that I still had the world. I decided, "Eh, why not." I opened it and realized why I had lost interest. I had been experimenting with mods, and had discovered an item-spawning mod. I had spawned bedrock (being a noob), and placed it everywhere. I silently swore to myself, said goodbye to my dog in that level, and deleted the world.
About 6 days later....
My friend told me he had a server and I thought, "Why not join him?" He showed me the hotel at which the new players stayed and such. While playing around on the server, I noticed something very strange one day while I was exploring the surrounding land—a hole in a hill. I noticed a ladder and a couple of chests, but didn't think much of it.
Later that day I found a wolf, and made a server companion.
I had to get off for the night and didn't come on until the next day. A server message came up "Ah, Rikumo, welcome back." I said thanks to my friend and went on from where I was when I logged off.
"You did some nice work last night!" My friend stated.
I sort of laughed and, being the smart ass that I am, said, "I didn't know taming a wolf was such a achievement!"
My friend then gave a confused reply, "Oh come now, you did more than just tame a dog."
He then logged on and asked me to follow him. He lead me back to that hole I had found the day before. But now it was smoothed out, with a wood floor, a lot more chests, and a glass roof. ''Wait now.'' Déjà vu.
"Erm dude, I did not build this."
"Yes, yes you did. You were on at 9 last night."
"No, I had got off at 8."
"Weird, the log shows you on at 9. Perhaps it was the thief." ( The server was an offline server seeing how most of our friends were too lazy to buy the game and we had a kid go on and loot most of the chests for valuables.)
We brushed off the issue and got on with the day.
At about 12 my Minecraft crashed for 5 minutes. I came back on to my astonished friend.
"How did you do that?"
"Do what? I just crashed."
He explains to me: within the 5 minutes I was gone, my skin had changed, a dog appeared next to me, and the whole world changed (from what I can tell, into my single player map).
Then a sudden error happened. Sounds got distorted, and colors as well. My friend froze out.... well sort of.
His skin (Axel From Kingdom Hearts) slowly, one pixel at a time, changed to my past skin. A dog appeared.
"You let the dreams die, so these will die as well."
And just like that the server crashed. My friend attempted to restart it but an error appeared every time. "Unable to load map." It was deleted.
So next time you wish to delete the world, don't. Your past may come back for you.