My friend and I were playing together on PE (my world), and we took a short break. After returning from the break, I logged in and when we connected, she entered as a new player. This had never happened before, and we could not figure out how to fix the issue. This was especially irritating, as she had been carrying a lot of valuables and we have no idea how to get them back, and her logged in correctly. Both of us were connected to WiFi, and I kept logging out and restarting my phone multiple times, but to no avail. I would like to know what can be done to fix this problem. Thank you! 

I do not feel this requires a screenshot, as it would not help explain the issue. 

Edit: I got a comment that this was a duplicate and to add more information. Unfortunately, I do not have a copy of my world before this issue, and am having difficulties finding out how to make a copy of the new world. Also unfortunately, do not have any photos of our inventory because we did not expect anything like this to happen. After some recollection, it was remembered there was 4 spruce planks, around 20 iron ingots, an iron sword with Fire Aspect 1, and a bow with Power (unsure of level) and some other enchantments. Not sure if that helps though, but we really wish we had something else to help us get our stuff back. Also this was on multiplayer, I believe. 

Edit 2: We joined again, and she got all of her things back. I'm not sure how it happened, but it was still concerning.