[rajasri]

Most of the times we get this error "500 internal server error contact your webmaster at webmaster@site.com" in our site.
We don't know what may be the reason Below are some of the things needs to be chacked.

• Check your .htaccess file for any error
• Take a backup and delete the .htaccess file and you came to know whether cause is because of that file
• Check errors in robots.txt file
• Check the sites index.html file for any errors or automatic scripts that your server not supports due to overload
• Do a restore of the settings in cpanel like mime settings etc
• Restart the Apache server by entering in to shell access from your cpanel
  

If you found more information provide us by comments happy problem solving.