Emergency - Bug on a joomla website. Site is down...

I upgrade joomla 1.5.11 to joomla 1.5.15 and it made a bug. On the back end, it writes "No input file specified." I can not even enter in the administrator section. On the frontpage, it writes: Warning: require_once(/home/thailawo/public_html/includes/[login to view URL]) [function.require-once]: failed to open stream: Permission denied in /home/thailawo/public_html/[login to view URL] on line 21 Fatal error: require_once() [[login to view URL]]: Failed opening required '/home/thailawo/public_html/includes/[login to view URL]' (include_path='.:/usr/lib/php:/usr/local/lib/php') in /home/thailawo/public_html/[login to view URL] on line 21 I need someone to correct this AS QUICK AS POSSIBLE, meaning NOW or TODAY. Not tomorrow. I have no idea what happened. The website is at [login to view URL] Thanks.