Before I was using Gnome desktop on Ubuntu 14.04 , then I installed Xubuntu desktop and just these days when I login it doesnot work..I dont know what's wrong when I drag something it repeat many times and stay on desktop and nothing work!...but gnome still ok...how can I restore Xubuntu desktop?
If you want to revert back to Gnome, then you should first remove XFCE desktop then reinstall Gnome desktop.
sudo apt-get purge xfce4 sudo apt-get autoclean sudo apt-get autoremove
reinstalling Gnome desktop:
sudo apt-get install --reinstall gnome-shell sudo dpkg-reconfigure gdm sudo apt-get update && sudo apt-get upgrade