I'm running Ubuntu 12.04. Everytime I clicked on the file icon of the file manager previously it displayed a list of partitions on the left hand side with the right portion being the files in my home directory. But last night a list of partitions disappeared from the file manager and all that is displayed now are the files in a given directory. After this initially happened, I rebooted my computer to no avail. I had about 7 partitions. When I tried running NTFS Config Tool last night it showed only four partitions. Today after reboot and it sees all but one partition that was there previously ie it now sees six partitions; however, my file manager is not displaying them. It only thing I changed yesterday was the configuration of my workspace windows from only 1 to the default 2 horizontal and 2 vertical. I also pressed the default button in the System Settings->Apprerance section. But I know that the default for Ubuntu is to display the partitions on the left of the file manager window so I am completely baffled to what could have caused it and what I can do to fix it.

The problem was the my sidebar got somehow un-clicked. I fixed it by clicking View->Sidebar->Show Sidebar.

Thanks for the update and solution.