how to change the language of the game?

silverchariots2​  Try playing in a clean user folder, just to see whether there's any residual content in the old folder that's getting in the way.  Move or rename the Sims 4 folder in Documents > Electronic Arts, and when you open the game, a clean folder will spawn with no content.  Start a new save and have a look around.  If everything is fine, you can move your old saves and anything else you want to keep to the new folder.  Keep in mind that the sims' names won't change when you change the language.

If the game is still in English in a new folder, you'll need to uninstall and reinstall the game.  I'd suggest a clean uninstall since the repair process didn't work, and it's not much slower than a regular one.  Here's how to do it:

📓[GUIDE] [PC] How to Clean-uninstall Sims 4 | EA Forums - 12636503