How to restore Application launcher?

view full story

http://askubuntu.com – I played around with compiz manager, for some reasons, the unity disappeared. Now it only shows my desktop. I tried to open terminal using Ctrl-shift-T but it doesn't work at all. Click on help, it's just freeze. In fact, double-click on anything would make it freeze! I've just installed 11.10 couple hours ago. The only thing I can do now is right click on Desktop and change desktop background :(. What can I do? I wish I never upgraded to 11.10! (HowTos)