I made a survival world a month or two ago and got very far (the end, many farms, etc). I launched Minecraft and did not see my world. Checked the save folder and I had the file. I have many backups but the newest one is a week ago. Renaming the level.dat_old file did not work. The game didn't crash but I may have Alt+F4 out. I didn't use any mods except Optifine. This world means a lot to me so it would suck if I had to go back a week. Hopefully, someone replies.