[ubuntu] No nVidia drivers work in 16.04

Using any nVidia driver results in a black screen on boot. In my opinion this is a very important issue that is being ignored. I am using a nVidia Optimus laptop and have been using Bumblebee since 9.04 (it had another name back then, I forget what it was), to switch between the intel and nVidia GPUs. Since "upgrading" to 16.04 not only does Bumblebee no longer work but if any nVidia driver is installed the GUI and Unity fail completely. Below is a solution if you find yourself locked out of your system because of this problem but a solution to the nVidia driver problem is needed urgently.

If you find yourself locked out of your system this is the solution that worked for me:

*) In the grub menu select the partition you want to boot and the press "e" and then replace

....ro    quiet splash .....

....ro    nomodeset quiet splash .....

sudo apt-get purge nvidia.* bumblebee