can't display the front page

不小心把access content 在authenticated 裡unmark 了, 現在不能display 我的 website 的front page. 如何可以解決呢? Please see the error message as below

Thanks.
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Site off-line
The site is currently not available due to technical problems. Please try again later. Thank you for your understanding.

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If you are the maintainer of this site, please check your database settings in the settings.php file and ensure that your hosting provider's database server is running. For more help, see the handbook, or contact your hosting provider.

The mysqli error was: Access denied for user 'username'@'localhost' (using password: YES).