Damn... that sucks.
Though I can't imagine how that happened? What do you remember doing with it before you saved?
I was duplicating it about to make room for a carrier I'm making, made a big pretty box around it that fit it, moved it to the side and pasted it. Removed the original, everything was fine, walked on it a bit (so it wansn't just a ghost render or anything). I then proceeded to paste it next to itself like 10 times because I thought it looked cool and wanted to test the new duplicator.
Actually now I put it like that I think I know what happened, I prolly undid it one time too many when I removed the 10 dups and removed the original, which stayed as a ghost render forgetup (you know the ones that drop your framerate to like 5fps when you fall through them, and have no collision), worked on the carrier a bit then saved. So it's nothing to do with the duplicator in that case.
EDIT: forget my luck I forgot to reinstall save saver since I reinstalled Blockland like 2 weeks ago so it's loving permanently gone too forget me forget this forget blockland.
I can rebuild it twice as fast with the mirror function though so that's nice.