@milesmilena Please open Documents > Electronic Arts. You should see a folder labeled "The Sims 4," which contains the data from when you've played the game in English. Hopefully there's also a "De Sims 4" folder containing your saves and other user data from when you've played in Dutch. These two folders are not interchangeable: the game will read whichever one corresponds to the language it's currently using.
You could of course move your content from the "De Sims 4" folder to the "The Sims 4" folder and pick up where you left off. But if you prefer to keep playing in Dutch, just uninstall and reinstall the game, and it should go back to reading the proper folder. If the App installed the game in English despite your choosing Dutch, set the App to run in Dutch this time. If you don't see the option to install Sims 4 in Dutch, let me know.
I'd also suggest making a backup of the "De Sims 4" folder, or at least the saves and Tray folders inside, before doing anything else. That would protect you against other computer issues that might otherwise wipe your Sims data.
If you can't find your old saves, please see this thread:
