i don't know how to search my problem cause i don't know how he call the things on the bottom bar at unity.
I installed Gnome fallback from ubuntu software center and i choose GNOME CLASSIC ( no effects )
and two minutes later i deleted by Alt + Delete from Panel option.
and it turned into:
(i add the logout button to go back to unity to write this question)
the problem is not in unity but in gnome session.
Gnome (after my stupid action) picture
I used this GUIDE to take the idea to download Gnome. And i looked only the 12.04 guide.
i think that my question is useful, please add comments below if i miss to say something that is important. Thanks, George