Today, I've had the second occurrence of this particular issue. Not too long ago, I loaded up my survival world only to find that I was placed back at my original spawn location when I first generated the world. Fortunately, one of the homes I built is not too far away, but my biggest gripe is that I've lost all my experience, inventory items and armour. I return to my houses and the items contained in their chests are still in place, but as you can imagine I still lose a lot of stuff that I had in my inventory. Today was the second time I've had this occur, the last time was a few days ago.
The only mod I have installed is Forge, and I'm launching through Forge. Does anyone have any suggestions for me?