After closing ArtiosCAD without saving your design, can you restore it even when the AutoSave Recovery window did not appear for you?
In case you have activated Activate AutoSave, for example, every 5 minutes via Defaults > Startup Defaults > AutoSave Options, after 5 minutes, an Autosave file will be stored temporarily in your local Temp folder, for example: %TEMP% or %userprofile%\appdata\local\temp; the file name can look like Bck0001.AAS.
As soon as you close ArtiosCAD, however and select NO for the question "Do you want to save your changes?", this .AAS file is removed and cannot be restored. It doesn't matter if the file had already been saved once or not.
In case of a saved file, you won't be able to restore it to the latest state; you can reopen the saved file without having the latest changes.
Only in case of a crash of the program or a forced quit, the .AAS file will be retained. As a consequence, when restarting ArtiosCAD, the AutoSave Recovery window will pop-up, giving you the option to select the file(s) you want to restore: