In my research on Unity issues, I've observed that several users see nothing on the desktop after logging in (no sidebar, no top bar... nothing), just the background image. Even worse, when you press Alt+Ctrl+T, the terminal window doesn't show up either.
Fortunately, I've found a few solutions to this problem as well, which I'll share with you here. The goal is to help those who have unsuccessfully faced this problem in the past or are currently struggling with it. Of course, if you haven't run into such a situation yet, it can't hurt to gain this knowledge.
Now let's move on to solution 1, which is to re-enable the Unity plugin. The steps in the following screenshot explain how you can do that:
If the aforementioned instructions don't work, then here's the second solution:
Launch a tty terminal by pressing ctrl + alt + f1. Once in that terminal, run the following set of commands in the same order as listed here:
sudo rm -rf ~/.cache/compizconfig-1 sudo rm -rf ~/.compiz sudo rm -rf ~/.Xauthority sudo dconf reset -f /org/compiz/ setsid unity sudo reboot
If the first solution didn't work, then this one should definitely work. In case you used a different solution to resolve such an issue, share that with us in the comments below.