I just uninstalled all cairo dock related stuffs from my ubuntu 13.10 using 'purge remove' and now my present graphics(colors and stuff) are way different from my default(when I installed it). Can someone please explain what shall I do to bring it back to default settings.
Yep, search for software and updates then click on additional drivers you will see a list there. Choose the driver you want.
To reset the theme open terminal Ctrl+Alt+t and use
gsettings set org.gnome.desktop.interface gtk-theme '' gsettings set org.gnome.desktop.wm.preferences theme '' gconftool-2 --set --type string /apps/metacity/general/theme ''