You have classic encoding corruption. The file contains the ASCII characters (e.g., "k a g a" stored), but without the Abbasi font applied, they look like English letters. You need to:
Start typing using the Remington layout. If you are used to Unicode/Mangal, you may need a layout map for reference. 💡 Pro-Typing Tips abbasi hindi font keyboard layout
The Evolution and Significance of the Abbasi Hindi Font Keyboard Layout You have classic encoding corruption