I just updated my MC because i wanted to play with my friends and i host the world, and it just deleted all my data and signed me out, i tried  going to %LocalAppData%\Packages\Microsoft.MinecraftUWP_8wekyb3d8bbwe\LocalState\games\com.mojang\minecraftWorlds, ** but it has nothing, i think Mojang just deleted all my data and we've been working on that world for the past 3 months.