Unity Launcher disappeared - why?

Question

Basically, when I press Super it looks like this:

As you can see, the Launcher is missing. I have no idea why this happened.

I have already tried the following:

• removing folders: ~/.compiz-1 and ~/.config/compiz-1 and running unity --reset,
• reinstalling Unity with sudo apt-get install --reinstall unity,
• reverting all sidebar settings to defaults in Ubuntu Tweak,
• checking that the Unity plugin is enabled in CCSM (as described here),
• restarting the system.

None of these helped. Do you have any other ideas? How can I find out what happened?