It's saying the problem is located in the wp-login.php file, which should be located in your root install of WordPress.
The problem with these kinds of error messages is that often times you'll fix the problem in that file, but that then will result in a different file's error message.
Since that file is part of the WordPress core files, you can try Upgrading WordPress to the latest version number. Obviously you can't log in so you'd have to do it manually.
Here's WordPress' official guide on doing it, and here's a video showing you how to do it.
Hopefully that will solve your problem.