Sounds similar to another post, but it is different.

Created a terrain, edited for a few hours, and closed the tools. When I came back and loaded my world, the hierarchy was empty, and the files I'd created earlier were visible in the resource browser. Seen the recommendation that I shouldn't be working in the root folder, so I restructured my directory, and it worked! I worked on my terrain for several more hours, closed the tools, and when I opened my world later, it was blank again. Empty hierarchy, files in the resource browser. I lost all of my work, and several evenings now not

current directory is: My Games\ArmaReforgerWorkbench\addons\ColdDay\Worlds\ColdDay

in there, is my Layers folder, and my terrain folder, along with my gproj and ent files.