How can I fix this error?

Warning: require(/home/plugless/public_html/wp-includes/pomo/mo.php): failed to open stream: No such file or directory in /home/plugless/public_html/wp-settings.php on line 85
Fatal error: require(): Failed opening required '/home/plugless/public_html/wp-includes/pomo/mo.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/plugless/public_html/wp-settings.php […]

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