the next step after not panicking is as follows!
Now scroll to the very bottom of the page. You can actually scroll to the very bottom of ANY page, but the settings one is shorter than going through miles of Facebook posts. At the very bottom of the page off to the left, you’ll see the language that Facebook is being displayed in. Even if it’s written in a different language that’s still where to click.
Click on it and you can change the language back to English.
If you can do this, it’s highly unlikely that anyone actually hacked your Facebook account. I know sometimes people use the term “hacked” when they’ve left their Facebook page open and someone posts something on it as a joke, but when I say hacked, I mean someone broke into your computer. Changing languages is a common joke people play. It’s also possible to accidentally change languages by clicking in the wrong place or bumping your touch screen. Another popular joke is to pick “upside down English” for a setting.
(note: happy to report that the switched language was indeed the problem with this account and it was back to English in just a couple of clicks.)