This is a question in general. Sometimes when using Natty, the interface freezes like the keyboard works but the mouse does respond. In which case pressing Ctrl+Alt+F1 puts me at the terminal. However I do not know how to load the GUI and Unity and continue using Ubuntu. At present I just shutdown properly and restart.
I have no expertise in this regard, which is probably why some of the terms I use could be wrong. Please correct me if necessary.
How do I restart the Xserver or GUI(Gnome and Unity) when I press Ctrl+Alt+F1?
There are a few ways to do this. My personal favourite is to login to the F1 text console as yourself. Then type
This should kill you previous X server and restart it. Sometimes it fails to kill properly, but it will start another X server on tty8 (CTRL + ALT + F8)
You can restart X in 2 different ways staying at graphical tty (i.e. tty7).
First you can try
Ctrl + Alt + Backspace
(this shortcut isn't enabled by default. To enable, go to Menu > System > Preferences > Keyboard > Layout > Options > Key sequence to kill X server).
If it doens't work you can use the kernel to do this. The "shortcut" is:
Sys Rq + Alt + K
(or for laptops:
Fn + Sys Rq + Ctrl + Alt + K)
For reference, see Wikipedia: Magic SysRq key.
If you can use
ALT+F2
you can try"unity --replace
" OR "unity --reset-icons
"