[SOLVED] JAuthentication::__construct: Could not load authentication libraries

Oh my God! I got this TERRIBLE problem!
Always when I am trying to enter my admin account on joomla adminsitrator I get this message:

JAuthentication::__construct: Could not load authentication libraries

I cannot acess my account!

I was seeing how to fix it and it seems I have to acess my cpanel of my site but I don't know how to acess that, because my site is on my php.

It started when I go on the language archive of the footer to remove the Joomla words. It worked. So I went try to remove the
Copyright © 2009 YouTravel. All rights reserved Custom Design by Youjoomla.com
RSS | CSS Valid | XHTML Valid | Top
But I just open the index.php and the joomla.php
I did not change anything in these things!

I am afraid of have to start my site again!

Could you help me or it didn't have a solution?
Should I restore something on php files or it isn't a problem?