wp-db.php reckonthat.org

HELP!!

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Fatal error: require_once() [function.require]: Failed opening required ‘/home/content/m/a/r/maryandpaul/html/wp-includes/wp-db.php’ (include_path=’.:/usr/local/php5/lib/php’) in /home/content/m/a/r/maryandpaul/html/wp-includes/functions.php on line 2539