ok, this can be fixed, but involves a lot of delicate steps. I suggest you write them down:
1. Boot to your 1st Fedora cd. On the Fedora splashscreen, before the install starts, type "linux rescue."
2. Follow the dialog, and if asked, allow the cd to mount the hard disk in read-write mode (can't remember the exact phrase, because I don't have my cd available.)
3. When it is done booting, create a directory to mount your Fedora partition.
4. Mount your Fedora partition on this new directory.
where hdx = the partition where you installed linux. (If you are not sure, you can do . This should show you all the partitions on your disk.
mount /dev/hdx /mnt/fedora
5. This step is only necesary if your /boot folder is on a different partition. Otherwise, go to step 6.
If your /boot resides on a different partition, mount it under /mnt/fedora/boot.
where /dev/hdy is the partition where your /boot resides.
mount /dev/hdy /mnt/fedora/boot
6. You're almost there. Now, you have to tell linux to treat the /mnt/fedora folder as the root of linux. This will make all the folder settings match your installation.
7. Finally, reinstall grub to the MBR of hda.
8. If there were no errors, reboot the computer.
Please not that, if your hard disk is a SCSI, SATA or PATA drive, your installations wouldn't be /dec/hda but /dev/sda (most likely).