This problem actually appeared out of the blue. I've nearly exhausted every option I can find here, but it barely helped.
Here is my situation:
I tried
ccsmto enable Ubuntu unity plugin, but every options are unchecked and it seems every time I configure and exit, it revert back to "everything unchecked".My guest account seems working normally.
Reinstalling
ubuntu-desktopandunityalso didn't help.After trying
export DISPLAY=:0sudo dconf reset -f /org/compiz/ setsid unity
Unity launcher and the panel flashed for a split of a second and then disappeared again