Ctrl+Alt+F1 to F6 are the virtual consoles provided by the getty / agetty programs. Ctrl+Alt+F7 is the console where your X server is running. The GUI (Gnome/KDE or any other) runs over X. You have to put Your username & Password and you are good to go. So to get back into your GUI window manager, Press

Ctrl + Alt + F7             or                 Alt + F          or               Ctrl + Alt + F8

— If nothings happens, Press Ctrl + Alt + DEL (delete key)

It will reboot your System.