The easiest solution will be to reinstall Fedora. I assume your /home is a separate partition, but make sure you have a backup of it just in case.
The much more complex solution is to boot one of the net install images using the rescue mode option. Then you can chroot into the existing system and reinstall grub2 and the kernel. The rescue shell will not be able to mount the /boot partition so you will have to mount that yourself first and fix the /etc/fstab file with the new UUID. Make sure you are editing the file in /mnt/sysimage and not the one from the boot media.
You formatted the file system of what partition?
/
(root file system),/boot
,/boot/efi
,/home
? That's an important piece of information. As for/
,/boot
, or/boot/efi
just reinstall Fedora (assuming you have a separate/home
). Make a backup of/home
in case something goes bad./boot one .