Fatal Error in taxonomy.php

I’m using WP version 4.2.2.
I’m able to FTP into my site.

Yesterday, my website was fine.

I check this afternoon, and now I get this error:

Fatal error: Call to undefined function get_taxonomy_labels() in /home/content/10/3593710/html/wp-includes/taxonomy.php on line 359

I have no idea what could be wrong with this file. I don’t see anything wrong with it, but then again, I don’t even know what I’m looking at. I don’t know PHP code.

What on earth could have happened here?

Here’s the entire file:

[ File redacted, do not post code like that here ]