Ensure you are manually saving at the typewriters in-game wherever possible. Starting a new game will also overwrite any existing autosaves.

If the game crashes or unexpectely fails, there could be a risk that save files are corrupted and need to be deleted. You can check in-game to see if you've reached the save file limit, and delete any older saves.

If an autosave file wasn't created, restarting from a previous manual save or restarting the level (if possible) is recommended to progress through the game. 

Restarting a new game is only recommended if all saves have been lost due to an unexpected error.