This simple tutorial will show you how to easily get back hibernate option in system menu with 3 commands in Ubuntu 12.04.

Hibernate has been disabled in Ubuntu 12.04 by default. ppa:vanhoof/policykit-d-p-hibernate-enabled contains a rebuild of policykit-desktop-privileges that re-enables hibernate, also fixes hibernation not wake up problem(if any).

Open terminal via Ctrl+Alt+T, and execute 3 commands:

sudo add-apt-repository ppa:vanhoof/policykit-d-p-hibernate-enabled

sudo apt-get update

sudo apt-get install policykit-desktop-privileges

Restart your machine, and see effect!