Restore original appearance and theme

Restoring default Ubuntu theme and appearance after installing some nasty themes which slows down performance of system.

Open up a terminal
Applications -> Accessories -> Terminal

We need to remove all these sections, they store gnome settings
The folders to remove are: .gconf, .gconfd, .gnome, .gnome2, etc.

So do this command:

$rm -Rf .gconf .gconfd .gnome .gnome2

Then log out and log back in (or reboot if you prefer)