Maybe your game files somehow got corrupted when you saved your game.
Fortunately, each time you save, AGS creates backups of your game files in the game's folder.
You can try recovering your game by renaming
ac2game.dta to broken_ac2game.dta
acsprset.spr to broken_acsprset.spr
editor.dat to broken_editor.dat
backup_ac2game.dta to ac2game.dta
backup_acsprset.spr to acsprset.spr
backup_editor.dat to editor.dat