sudo chmod -R 777 / sounds like an incredibly bad idea. If you ran that command successfully, you will probably want to reinstall your system right away, since you made all your files accessible and executable.
Ubuntu systems don't have a root password by default for security reasons. Users in the
sudo group can run any commands as root using the
sudo command, but you should think twice, because you can (no, you will) break your system if you don't know what you're doing. If you really want a root shell, you can get one with
sudo su -. You have been warned. To read more about how to use
sudo, please refer to the Official Documentation.
About installing ruby1.8, that's a quite different question. Since ruby1.8 has been removed from the official repositories in 14.04, you will have to use a PPA like this one.
sudo apt-get install python-software-properties
sudo apt-add-repository ppa:brightbox/ruby-ng
sudo apt-get update
sudo apt-get install ruby1.8
Check out the referenced website for further information.