Hi guys, this is urgent, my notebook is running on battery, suddenly the desktop gone blank after reboot, I only know how to start the terminal and Firefox to post this, I tried to re-create the panel by 'killall panel' and then 'gnome-panel', but I got error message 'can not register gnome panel...' something like that, I even try to reinstall Ubuntu-deskop but can't as it already installed, since I don't know how much battery left I would be very much appreciate if someone can point me to the right direction w/o reinstall the whole things asap, thanks a lot !!

Update : I forgot to mention it was the classic desktop missing, but I can boot to the new default desktop normally, I think this is easier to fix huh ?

Yes, if you have a desktop, use it. You should be able to go into synaptic package manager, and mark gnome for re-installation. Try that, and see if you get back to normal.

I'm not sure if reinstalling the ubuntu-desktop package is the right move but if it is, you should be able to run the following:

sudo apt-get -y purge ubuntu-desktop ; sudo apt-get install ubuntu-desktop

That will purge the ubuntu-desktop package and then reinstall.