I had the same problem (among many others) on a system where things got corrupted after tweaking and replacing disks in a RAID array.
In my case this problem was caused by that the upstart package simply wasn't there. Lots of files from this package reside in /sbin which in my case was nearly empty.
I managed to fix the issue by re-installing upstart:
Code:
sudo apt-get --reinstall install upstart
... Actually it was a bit more tricky for me since the dpkg package was damaged as well (which prevents the command above) and it seemed like grub was not properly installed either.
In case this happens to someone else, here is what I did (which took a lot of time and Googling to find out):
I used a live CD (must be same Ubuntu version and architecure, e.g. 12.04 x86_64) and started the computer.
To "repair" dpkg I manually copied the file /sbin/start-stop-daemon, which was missing, from a package as described here:
http://ubuntuforums.org/showthread.php?t=1449322
(The corresponding file from my live CD was probably sufficient, but I thouhgt of that first later on.)
Then I chroot:ed into my installation (still using live CD) using the instructions found here:
https://help.ubuntu.com/community/Gr...ing#via_ChRoot.
Before re-installing grub (described in the last few steps in the link above), I could now re-install dpkg:
Code:
apt-get --reinstall install dpkg
Then in the same way I re-installed upstart:
Code:
apt-get --reinstall install upstart