I was working on my map. I did some work in MCedit then closed the map and opened it in minecraft. After a short time the game crashed - 'java ran out of memory' which happened to me a few times before (crash report included).
I started the game again and while i was waiting for the game to load I tried to open the map in MCedit but it caused error - 'don't know how to open - level.dat is missing'.
When I opened appdata > roaming > .minecraft > my map there was no level.dat or level.dat_old. It just dissapeared causing me to lose many hours of work since my last backup.

Btw is there any way to get it back?