Chest deleted contents when I closed world, and I can’t get contents back

I put a few items in a standard chest including enchanted books, tools, and a few stacks of cobblestone. I went to a different app without closing Minecraft, (I didn’t save and quit) and when I came back, the chest was still there but my items were gone. This was a single player world, so nobody stole my items, so I don’t know how they went missing.