I am fairly new to Ubuntu ( I have been using it for about a week and a half). I am using 14.04 LTS 64-bit. I immediately installed a bunch of apps. Everything was working well. I tried out a couple of other desktops (GNOME 3 and LXDE) and they both worked fine. I tried to install Pantheon with this tutorial:
but on logging out I did not see Pantheon in the list of desktops. I logged into Unity, and found my desktop empty, with no icons (the launcher had the same icons, but the Files, System Settings and Software Center icons have all changed). The background had reverted to the default image (I was using a downloaded image). The top black menu bar was missing and in the top right corner all the icons were different. I was able to find all my applications in the Dash, and they were all working. I checked home/user/Desktop and they were all there. I tried dragging them from the Dash to the desktop, but to no avail. I tried to change the desktop background in Settings, but it was already linked to my downloaded image. I logged into GNOME, and my desktop icons weren't there either. However my downloaded image was in the background. Shortcuts like the super button and Ctrl+Alt+T weren't working in either desktop. . I logged into LXDE and everything was working fine. The desktop icons were there and my image was in the background. Shortcuts were working. I was mainly using Unity, so this is very annoying to say the least, and I need an answer soon.