Well, your fedora system is lost now. You have to reinstall it, that will reconfigure grub for you.
If you want to boot your windows system, you can enter the following commands in the grub shell (the thing you have now at boot). Use tabulation for the completion.
I've presumed here your windows is the the first partition, which is the most common case.
I don't know, but maybe the 'fixmbr' command can be used from windows ?