Out of what ever reason, the grub2 bootloader never installed. Boot into live mode, open terminal and execute one by one these commands to enter inside your hdd installation and install grub2 (the package name is officially grub-pc):
I am breaking them down to be easier to view, you just keep executing line by line:
sudo mount /dev/sda1 /mnt
sudo mount --bind /proc /mnt/proc
sudo mount --bind /dev /mnt/dev
sudo mount --bind /sys /mnt/sys
sudo chroot /mnt
apt-get install grub-pc
If during execution some error shows up, make sure you typed the command correctly. If yes, stop executing the commands and tell us exactly the error message and after which command it showed up.
sudo umount /mnt/sys
sudo umount /mnt/dev
sudo umount /mnt/proc
sudo umount /mnt
If you finish all of the above without errors, restart and hopefully ubuntu will boot.