Support

You have forgotten some basic information which could at least give me a remote hint as to why this is related to my software so that I can attempt to help you. For example, did you try to restore a backup? Did you enable a plugin I am making? Did you install or upgrade any of my software? If so, which one? I would love to skip this step, but I am afraid I am a lousy mind reader and I am, unfortunately, not sitting in front of your computer or have access to your site – not to mention, I don't even know what your site is.

All right, now we have something to work with :)

You still have your backup files. They are most likely stored in your site's administrator/components/com_akeeba/backup directory – unless you changed the Output Directory. Move the lastest of those files to your site's root (where you can see index.php and the administrator, components, ... directories). Upload kickstart.php to your site's root and rename your .htaccess to htaccess.old. Now run kickstart, e.g. http://www.example.com/kickstart.php to start the restoration. Take a look at the Quick Start Guide for step-by-step instructions on the restoration.

If this doesn't help, you will have to follow the post-restoration basic troubleshooting instructions.

If you still have a problem, I will need you to supply all the necessary information you skipped in your initial post:
Joomla! version: (unknown)
PHP version: (unknown)
MySQL version: (unknown)
Host: (optional, but it helps us help you)
Akeeba Backup version which took the backup: (unknown)
Kickstart version used to extract the backup: (unknown)