$ rm -rf ~/.compiz* ~/.config/compiz* ~/.cache/compiz* ~/.gconf/apps/compiz* ~/.config/dconf ~/.cache/dconf ~/.cache/unity #删除dconf配置信息
$ dconf reset -f /org/compiz/ #重置Compiz
$ setsid unity #重启Unity
$ unity --reset-icons #重置Unity图标(可选)
实在不行就重新装ubuntu桌面
$ sudo apt-get install --reinstall ubuntu-desktop
$ sudo service lightdm restart