Update Grub2 on Ubuntu Server 14.04

 It's really very easy. Use a text editor to open /etc/default/grub like so:

sudo nano /etc/default/grub

Then find the line that says GRUB_CMDLINE_LINUX_DEFAULT="" and add nomodeset inside the quotation marks.

If you do use nano then you can press Ctrl-o and Ctrl-x at this point to write and exit.
Then run this command:

sudo update-grub

and that should do it.