wp-config.php and wp-load.php error

My site has been working fine but when I logged into day I got the following error message

Warning: require_once(/home/bob2612/public_html/rtbathroominstallations.com/blog/wp-config.php) [function.require-once]: failed to open stream: Permission denied in /home/bob2612/public_html/rtbathroominstallations.com/blog/wp-load.php on line 29

Fatal error: require_once() [function.require]: Failed opening required '/home/bob2612/public_html/rtbathroominstallations.com/blog/wp-config.php' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/bob2612/public_html/rtbathroominstallations.com/blog/wp-load.php on line 29

Any idea how I can clear this please?