The problem is pbviosu in the error message:
Missing argument 2 for wpdb::prepare(), called in /homepages/9/d410734795/htdocs/app410734812/wp-content/themes/revelation-theme/lib/theme-sidebars.php on line 51
Your theme doesn’t call the $wpdb->prepare() function correctly, so it’s basically broken. You’ll need to use FTP to re-name yor themes folder so it will revert to the default theme, and then you can start looking at the actual problem.
http://codex.wordpress.org/FTP_Clients
http://codex.wordpress.org/Using_FileZilla
If you can find that file, you can see what is going wrong on that line.
Thank you for your help. I truly appreciate; however, what files do I rename and what is the name I should use?
Thanks again.
/wp-content/themes/revelation-theme/
Rename it to *anything* different. That will default back to the default theme.
As it’s a commercial theme you should go back to the vendor and ask them for support on fixing the problem. After all, their support is a part of what you’ve already paid for, and we don’t have any access to the themes code to figure out what’s wrong with it.