open this config.php and check once more if all logins and pass are correct.
maybe ip changed on server?? maybe you moved ... etc?? maybe you change login or pass to db and forgot to put it here?
btw - write if all you pages (index.php, rankings.php etc showing the same info...)
because its like this:
you opening
its loading whole content from index.php by adding all codes from config.php to this index...
so check your line 21 counting from 1st of your index and ending on config content...