Unity doesn't load, no Launcher, no Dash appears

1. 重新安装 ubuntu-desktop不起作用。

Enter the following commands:- Ctrl+Alt+F1 login there by user name and password

try sudo service lightdm restart

If lightdm fails to get back at normal :-

then Enter:- sudo apt-get update

sudo apt-get install --reinstall ubuntu-desktop
sudo apt-get install unity

$ restart unity-panel-service

2. 安装 compizconfig-settings-manager 可以工作。

Install compizconfig-settings-manager by running

sudo apt-get install compizconfig-settings-manager

Then run it by doing this:
```
export DISPLAY=:0
ccsm
```
The first part tells the terminal which display you want it to load on (otherwise it won't have a clue).
Press Ctrl+Alt+F7 (or Ctrl+Alt+F8 sometimes) to get back to the graphical display where there should be a CompizConfig Settings Manager screen sitting there.
Find the Unity plugin. Enable it.
Everything should spring into life but if it doesn't, you might have to restart. You can do that by going back to tty1 and running sudo reboot.

If unity still does not load try:
dconf reset -f /org/compiz/ unity --reset-icons &disown

Reboot if it doesn't work right away.

For 11.10 And Older

If you hope into a tty (Ctrl+Alt+F1 through F6) and run:

DISPLAY=:0 unity --replace

It will reset Unity back on tty 7 (Ctrl+Alt++F7).

You can also try just:

DISPLAY=:0 unity

But that won't work if a windows manager is already running on display 0 (it will give you an error, just use unity --replace in that case).

If Unity absolutely refuses to restart try this:

Install gnome-panel:

sudo apt-get install gnome-panel

Than run it on display 0:

DISPLAY=:0 gnome-panel

You should then have Gnome 2 style panels on your desktop, which you can use to logout.

In 13.04:

unity --replace is deprecated. Instead, use the following:

dconf reset -f /org/compiz/ 
unity --reset-icons &disown

Reboot if it doesn't work right away.