Why has Gnome 3 reverted to classic (Gnome 2) look and feel?
Let's try the simple way to fix it first, because that looks like the Gnome3 Classic look (which is, yes, very similar to Gnome2)
-
Open a terminal, and type/paste:
sudo apt-get update && sudo apt-get --reinstall install gnome-shell -
Logout
-
Click on the Ubuntu logo:
-
Select the Gnome session, and click back:
-
Login and see if you still get the Gnome2 look-and-feel.