All my items disappeard when i changed the 14w10c to 1.7.5

I was playing in the 14w10c, all quiet with no problem. Entoces wanted to play on a server, change version to 1.7.5 and started playing on the server, so I wanted to play survival, but i noticed something out of the ordinary, all my objects were gone, my armor, my picks, sword, everything! I went home and noticed That all my items on the chest disapeard, but not only in the chests, also in the dispensers. I do not know what happened but i want to know what happend. Thanks