I updated to 1.7.5 and lost my inventory

I updated to 1.7.5 and lost everything in my inventory and chests. I had backup save files and i tried to use them in both 1.7.5 and the previous versions, i.e., 1.7.4, 1.7.3, and 1.7.2. I'm not too sure on how to go about fixing this.