I spent ages building this huge structure but I decided to wait until the morning to do the finishing touches so I saved and whatnot. I came back this morning and the save was gone. I went through ALL my saves to check but it's 100% gone. Is there any way I could get it back?
Hey, this is quite a strange thing for Minecraft to do as you probably know. Before quitting your game, you should always quit back to the main menu before closing the game completely.
(If you're using Mac, i mean not quitting the game like command+Q while still in the world. I'm not familiar with Windows 'Force Quitting' system.)
Aside from that, put all your saves onto an external drive or somewhere on your computer where they'll remain safe and re-download the game. It's not uncommon for Minecraft to experience glitches and bugs, especially if you're running the newest version (which is 1.9.2 at this current time, I believe)