Hye just follow these steps, This tutorial will help you to change the language on Facebook if you never tried to do to is successfully:
• Open facebook on your browser : http://www.facebook.com.
• In the bottom left of the page click on the language you are using for example: English (U.S).
• Then a window will appear to choose the language you want.
• Then you will notice the facebook language will change and you can login…