thank you all for helping me to solve this out but as I thought it's something that happens during an upgrade, I installed gnome-shell and I'm able to log out freely also I did log out from guest session using Unity. So it's just something that happen to my account during an upgrade, I assume.
thank you all for helping me to solve this out but as I thought it's something that happens during an upgrade, I installed gnome-shell and I'm able to log out freely also I did log out from guest session using Unity. So it's just something that happen to my account during an upgrade, I assume.