Sorry to hear that.
Can you please tell me which platform you're playing on?
Windows, Mac, Web pc, Web mobile?
8 days ago (+1)
Paste this path on your file explorer
%appdata%/Godot/app_userdata/Modification App
(This should open the save folder on C:\Users\{YOUR_NAME}\AppData\Roaming\Godot\app_userdata\Modification App)
Then, open the "globals.save", and change the Fullscreen value from true to false.
This should open the game in windowed mode again.