Customize "Your search yielded no results" Text in Search Results Drupal

Below is the sample code for customizing the "Your search yielded no results"  message in Template.php file

function theme_name_box($title, $content, $region = 'main') {

  if ($title == 'Your search yielded no results')

  {

    $title = 'Sorry, we couldn\'t find what you were looking for';
    $content = 'Check if your spelling is correct.';
}

 $output = '<div style="margin:10px"><h3>'. $title .'</h3>'. $content .'</div>';

  return $output;

}