Session saving is the feature that restores everything, which you were doing right before you log out or shut down the computer, in the next time you log in. In Linux Mint 13, this feature is disabled by default but you can enable it easily.
In MATE, hit Alt+F2 and type "mateconf-editor" to open the MATE configuration window. On this window, you go to apps > mate-session > options and check the "auto_save_session" option and everything is done:
In Cinnamon, it will be a little more complicated. You need to install dconf-tools first to use dconf-editor. To install dconf-tools, the command will be:
sudo apt-get install dconf-tools
After dconf-tools is installed, hit Alt+F2 and type "dconf-editor" to open the configuration window. On that window, you go to org > gnome > gnome-session then check the "auto-save-session" and from now, session saving is enabled in your Linux Mint 13 box: