Yesterday I created a new Unity project and loaded the CF tutorial to test a raw file I'd created for someone at OGT. When I created the project I gave it a name.
Today when I hovered the mouse over Unity in the Start menu to bring up recent files, CFtutorial was listed, not the name I'd created. Strange I thought. So clicked on it. Then a Unity menu came up with my recent files. So I make a hasty decision and clicked on a different project I wanted to work on. Something starts decompressing, and I get a bad feeling.
Sure enough, that CF tutorial loaded itself on top of my existing project. Tried loading the scene file - nothing.
I was about to get righteously upset when I realised I'd recently backed the terrain up before doing adjustments around a hazard. Sure enough, it looks like I've salvaged the work. A custom rough layer I'd created is now gone from the library (although that layer still looks the same in the window until I click on it and it says its a bunker), but if that's all I have to fix I'm thankful.
TLDR back up the terrain.