Losing all items

Hello, today I experienced pretty unpleasant bug. I have snapshots allowed, so I loaded my world in snapshot 14w29b, but I was experiencing some lags like blocks disappearing like 5 secs after I mined it or some door problems. I closed MC and changed my version to last official 1.7.10, hoping that it will help. And after loading I lost all my items... in inventory, chests, item frames... simply all non-placed blocks. I didn't have any backup of that world and lost many hours building it, but w/e, I play just for fun... but I think it's something, that you should give attention .
However I'd be delighted if there was a way to fix it.

Sorry for my english if there are some mistakes, I'm not a native speaker