First you need to find out what partition in /dev your hard drive is. Run this command:
ls /dev | grep -E "[hs]da[0-9]"
This will give you a listing of your hard drive partitions. From there you need to figure out which one is the partition your looking for.
To do that, you need to try to mount it and then inspect the contents as root or sudo:
sudo mkdir /mnt/mydrive
From there you need to run the following command on the list found above:
mount /dev/<from list> /mnt/mydrive
sudo mount /dev/<from list> /mnt/mydrive
Inspect the contents of the drive and if it's not the one unmount it and try another:
sudo umount /mnt/mydrive