Could anyone help me with language, please? (Penumbra: Overture)

[DARIUSH2001]

You have to ask that youtuber to give you the .lang file. As far as I can see, the whole Penumbra games are English only.
EDIT: Look in My documents/Penumbra. There are your save files. You can copy the whole Penumbra folder from there on desktop, uninstall the game, install it again and put the Penumbra folder which you copied back to My Documents. That way you can reinstall the game without losing progress. You don't have to reinstall it though. Just ask that guy for the .lang file.