None of my game progress will appear on the first screen, nor on the in-game menu once I press "New game" and "Esc". I have looked through the files and it my progress is saved on my computer, but it will not show up in-game. How do I make the progress usable and continue my game?

Are you using any mods?

Are you using a mod manager. Some mod managers might be using a virtual game save folder.

The load menu is greyed out?