Helloo! Soo I bought the game yesterday and it's fantastic (amazing job). I did around 15 saves in total and when I opened the game now again, there's no trace of those saves, I even lost my achievements... Like it's the first time I start to play it...

What happened exactly and it doesn't view my saves??

Hello. The saves should be in a "save" folder in the same directory from which you run your game. The achievements should be in "user/game_data.json" along with other data.
Could you check if you still physically have those files on your system (especially the save files) and they're in the same place as the game? I don't know what could be deleting them, the game doesn't try to delete anything. Maybe the operating system is not allowing it to read files for some reason.