Terraria World Gone?!

I was starting up Terraria as I do every day. i picked my character, and selected my world, Quarty. I started loading the world, but it said it was unable to load. It gave me the option to load a backup, but I went back and tried a couple more times. I even tried restarting the game, but still nothing. I finally desided to load the backup world, but when it loaded, everthing was black, and three seconds in the game crashed (And I also got the Rock Bottom achevment for some reason) I went back in, and now the world has no name, the tree, which was origionally purple and green, with a bit of yellow, was back to regular purple and green. And where it says the size of the world, it says "Unknown world." When I try to enter, it does the same thing: The world is completly black, and eventually the game crashes. I don't know what is causing this, but this is my main world, and I'm hoping to get it back. Please help me.

Also, When I was starting up Terraria, it acted like I just started it for the first time (Asked for language, had diffault resolution and cursour color) But my char and worlds were still there. And when I started terraria this time, my other worlds and my char are still working fine.

Sounds like your save got corrupted. That's pretty bad and it's possible that it might not be gotten back. Googling the issue might be your best bet just in case others have better ideas.

Some things you could try to try is going to your game folder and finding the world data. Does it actually still exist? Both a .wld and a .bak? You should copy those elsewhere just in case, remove the .wld and rename the backup to .wld so that the game is forced to reload the backup in case that works but for some reason it didn't want to load it. While you're there, you might want to see the size of the world file. If it's very small, then that seems like an empty world. If it has a bigger size, then the save should still actually have some data.

If you have Windows 7, right clicking the world file and choosing restore the previous version might find a non-corrupted save. I don't know if it's that simple on Windows 8 or 10, though a Google search might help you if you can't find a way to do it.

Try to do manual backups of your save files occasionally just in case.