problem in website viewing Fatal error: Call to undefined function omega_theme() in /home/itcom/public_html/sites/all/themes/libra/template.php on line 27 


Whenever I browse my site, I get this message, and I am not able to login to the site. Clean URLs are not enabled in this site. 

I would like to know how I can change the default current theme from code, and any other solution to rectify this problem.
The Libra theme is a sub-theme of the Omega theme, but seemingly the Omega theme is not present (otherwise, omega_theme() would be defined). Make sure that you have placed the Omega theme in /home/itcom/public_html/sites/all/themes/omega and try again.