Web site fails to open

Hi,
When I tried to open my website https://www.prithvirajbs.com I am getting the following error message. Till yesterday I was able to open the site without any problems. I shall be thankful if you can suggest any method by which I can solve this.
Thanking you in advance
Prithviraj B.S.

Warning: require(/home/prithraj/public_html/wp-includes/pomo/mo.php) [function.require]: failed to open stream: Permission denied in /home/prithraj/public_html/wp-settings.php on line 83

Fatal error: require() [function.require]: Failed opening required ‘/home/prithraj/public_html/wp-includes/pomo/mo.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/prithraj/public_html/wp-settings.php on line 83