All Achievements & Statistics are gone!

Okay, so I got on my world, and then I went on my inventory. Then all of a sudden, I earned the Achievement "Taking Inventory". I looked on Achievements, and my Achievements were gone except for my "Taking Inventory" Achievement! I looked to see if anything else was wrong, and my Statistics were gone, too! Please help me!

Update: My world is messed up, too! My neighbors are far away from me, rather than being next to my house!!! My world is distorted...