Darn happened to me as well but then i am a complete noob at this game and didn't really expect to get hooked on it as i have.
Thanks for input Truebador.
I knew it auto saved but i didn't know it overwrote the file everytime, until i looked for the saves.
Only thing is though i could put all the machines back etc, my erm whats it called, like dirt blocks, bascially all ground blocks are screwed up as they not loading the textures, looks like i have fire icons in them. So guessing i would have to some how step the launcher back but i don't know how to do that. Shall search forums for solution and hope it works.