Ubuntu 12.04 LTS has passed end of life
Ubuntu 12.04 LTS has passed end of life. Exception: There is extended security maintenance for Ubuntu Advantage customers until April 2019.
So install mkusb in order to create a USB pendrive or memory card with a current version to try live and if it works well, install into the computer.
How to install mkusb in Ubuntu 12.04 LTS
Getting the repository Universe
This command line in a terminal window or text screen
sudo add-apt-repository 'http://archive.ubuntu.com/ubuntu/ universe'
will 'enable the universe distribution component for all sources', in other words 'install' or make available the repository universe.
The fastest way to start making USB boot drives is to install the mkusb PPA, install and update the mkusb package like all the other program packages. See this link
sudo add-apt-repository ppa:mkusb/ppa # and press Enter to accept it sudo apt-get update sudo apt-get install mkusb
The whole dialogue in a terminal window is shown in the attached pdf file. It will install pv (alongside mkusb), if you have previously installed Synaptic or some other program in order to install the repository (alias source) Universe.