I have applied Mac OS X theme to my Ubuntu 13.10, and then got bored adn tried to revert it. Instead of trying to change themes first from the Unity Tweak tools, I tried to uninstall everything I could from the Application center (Not the things that come with Ubuntu itself). Not I can see my Log In screen and enter my password, but then nothing happens. It accepts my password (the bar dissappears) and it stays there forever. The Wi-Fi, turn off the computer buttons on the top right works. But the screen does not continue to my desktop.. It just stays there waiting in my Log In screen..
Note: Guest logging in does not work either..