Only the game's title is saved. It's frustrating. I can't continue my work and I will never ever start a new project if this one was deleted.

I am guessing this is on the desktop.

Can you open it with a text editor (Windows has Notepad built in, and see what is there?

Yes, only the game name survived. I could go on a rampage, it's frustrating.

<!--Saved by Quest 5.8.6794.35054-->
<asl version="580">
  <include ref="English.aslx" />
  <include ref="Core.aslx" />
  <game name="Crossworld Castle">
    <gameid>4322d0e5-4381-4036-933c-3ffa5c60a68d</gameid>
    <version>1.0</version>
    <firstpublished>2018</firstpublished>
    <menufont>Georgia, serif</menufont>
  </game>
  <object name="room">
    <inherit name="editor_room" />
    <isroom />
    <object name="player">
      <inherit name="editor_object" />
      <inherit name="editor_player" />
    </object>
  </object>
</asl>

Okay, I found my game. I just recognized that the game exists twice. The older one is my project. The second one is this empty version. Why and how it was copied is another riddle. I couldn't do it if I want to.