Did this system ever boot or is it a new install?
The error you are getting does not likely have anything to do with a password but improperly configured bootloader. The link below is another to configuring Grub2, specific to Fedora.
https://fedoraproject.org/wiki/GRUB_2
Posting more detailed information would be helpful. Boot any Linux Live CD, go to the site below and run the bootinfoscript. It will produce a results.txt file which you can post here and get some help. There is a link to specific instructions on the page.
http://sourceforge.net/projects/bootinfoscript/