I have recently installed cinnamon on Ubuntu 12.04 with success. After installing MS Office with wine my menu got messy so I tried to edit it with alacarte.
After having found out that alacarte is not the proper way to edit it, I right clicked on the menu icon to edit. After just a few editing steps it breaks and cinnamon stopped working (no menus, no desktop icons, no applets, no window decoration, nothing). Now, when I login with cinnamon I just get the background image.
I can login with gnome though.
I have tried to completely remove cinnamon and nemo and reinstall it but it didn't help.
I have no idea of how to get any king of diagnostics so if you ask something please explain how to do it or post a link with explanations.
Many thanks for the help, I hope I will not need to format the pc again to make it work.