I am trying to edit this file to add "nomodeset" to the end of the line.
Is there any way to edit a buffer? Is there a work-around for this?

I am trying to edit this file to add "nomodeset" to the end of the line.
Is there any way to edit a buffer? Is there a work-around for this?

Open Ubuntu's configuration file for grub:
sudo nano /etc/default/grub
Edit the content of the variable GRUB_CMDLINE_LINUX to include the word nomodeset
Use ctrl+x to save the file and exit nano.
Update the grub boot script to use your new config with sudo update-grub.