Game Froze and took my Iron Blocks

The game was working perfectly fine and then it just froze randomly. Because of that, I closed the game and when I reopened the game. I didn't have my Iron Blocks in my inventory anymore, and I didn't drop them or put them anywhere else before the game froze, so where are they? Is there anyway i could just get them back because i dont want to put it in cheat because I don't want to lose my achievements.