Might have deleted kernel - where do I install grub?

Ubuntu 14.04 LTS

I might have deleted the Kernel whilst trying to delete 10GB of old kernels. I haven't switched the PC off yet.

@Karel suggests an answer in a virtually identical question: Might have deleted kernel, but haven't shut off computer yet but it is vague on how to find grub (boot menu) device. I don't have enough reputation to comment there.

His answer:

sudo apt-get install --reinstall linux-image-generic  
sudo grub-install /dev/sdX
sudo update-grub

Disks program shows that, I have one SSD (device sda), split thus:

|             | Extended Partition |             |
|             |     Partition 3    |             |
| Filesystem  |        129GB       |  Filesystem |
| Partition 1 |____________________| Partition 2 |
| 25GB EXT4   |     Filesystem     |  102GB FAT  |
|             |     Partition 5    |             |
|             |     129GB EXT4     |             |

The 25GB is Linux (bootable); the 129GB is Linux and the 102GB is W95 FAT32

So I'm guessing that I need to replace the middle command with either sudo grub-install /dev/sda or sudo grub-install /dev/sda1 When @Karel suggests to enter the device name, I don't know if he means me to include the partition number.