[ubuntu] Grub Rescue Prompt After Deleting Partition

I have two HDDs in my laptop:

HDD1: Two partitions; an Ubuntu 14.04 install and another storage partition (my pics, files, etc).
HDD2: A second Ubuntu 14.04 install.

Both Ubuntu OS's showed up in GRUB just fine until, using a bootable Ubuntu USB stick, I deleted the the Ubuntu install on HDD1 and added that space to the storage partition.
That was not the right thing to do, huh? Now I get a GRUB Rescue prompt when I tu on my laptop.

So now I have the following:

HDD1: Storage
HDD2: Ubuntu

How can I go in and fix GRUB so that I can boot to HDD2? Can I use the bootable Ubuntu USB stick to do it?

Thanks!