How to set up arch fedora double boot?

edit

I recently installed fedora on top of an arch Linux install with encrypted LVM set-up. I have the following list of hard drive partitions

• /dev/sda1 # /boot of arch
• /dev/sda2 # /lvroot, /lvhome of arch
• /dev/sda3 # fedora install

On installing arch Linux the grub boot was lost and only a screen came up with 2 fedora options. How do I get back to being able to use the arch install.

Edit: I tried a method suggested

grub2-install

From a fedora live boot but now I am getting a grub-rescue screen where I am getting only the following.

GRUB-RESCUE> ls
(hd0)

How do I rescue my install of arch and still be able to use fedora.