Splitscreen players lost everything

I use splitscreen a lot to play with my little sister. After the bug fix -which does nothing but ruin Minecraft - I loaded up a world me and her played in a lot and when she joined in, all her stuff was gone. I went to other worlds me and her played in and all her stuff in all those worlds was also deleted. Months of work wasted. I need at least something to make up for the loss of months of work. If you can't restore the data I need Minecoins or something. PLEASE FIX THIS!!!