Installed Plugin, changed code, site is not loading

I followed the instructions to install and activate the plugin. Then, I changed the code “next_posts_link” and “previous_posts_link” to the required:

<?php wp_pagenavi(); ?>

Saved, and nothing happened. So then I replaced the new code with the originals:

if ( get_next_posts_link() )
printf( ‘

• %s

‘ . “\n”, get_next_posts_link() );
}

and

if ( get_previous_posts_link() )
printf( ‘

%s

‘ . “\n”, get_previous_posts_link() );
}

But now the site is completely inoperable. I can’t open any page, nor get to the admin panel.

https://wordpress.org/plugins/wp-pagenavi/