WordPress Installation Error

Hi, I tried to install WordPress into my web server, but it shows an error message like this:

Warning: require(/home/webcopy/public_html/wp-includes/pomo/mo.php) [function.require]: failed to open stream: No such file or directory in /home/webcopy/public_html/wp-settings.php on line 85

Fatal error: require() [function.require]: Failed opening required ‘/home/webcopy/public_html/wp-includes/pomo/mo.php’ (include_path=’.:/usr/lib/php:/usr/local/lib/php’) in /home/webcopy/public_html/wp-settings.php on line 85

Please help me how to fix it.
Thanks in advance.