Hi,
Boot a liveCD, mount the fedora root partition, chroot into it, fire up the grub command line, select the /boot partition, and install grub. :
Code:
#mount /dev/sda1 /mnt/root
#chroot /mnt/root /bin/bash
#grub
>root (hd0,0)
>setup (hd0)
>quit
#exit
Then reboot your computer, GRUB should be back. Substitute sda1 by your root partition; root by the mount point of your choice; hd0,0 by the disk/partition numbers (the first disk being 0, same for the first partition.
Serafean