I am running Ubuntu 12.10. On the log-in screen, there is no Ubuntu icon for me to click on to change desktop environments. I know where it should be, but it is simply not there. Why is this? And how can I get it back??? I just installed Cinnamon and I would very much like to switch to this environment.

I apologize if this is has been addressed elsewhere, but I honestly did try to research before asking. I found several similar questions, but nothing that has answers that helped my situation. And an hour of Googling did not produce anything helpful at all.

Thank you for your help.