I am trying to install openvpn using apt-get, but I get an error during the process [As far as I understand the issue is with unattended-updates, which I could not upgrade due to apt-get porblem :/]. I cannot upgrade, install, autoremove or purge anything else [which I need to do since /boot is full. For upgrading I did update before trying]....

Trace [on sudo apt-get autoremove]:

0 upgraded, 0 newly installed, 79 to remove and 421 not upgraded.
35 not fully installed or removed.
Need to get 24.1 kB of archives.
After this operation, 140 MB disk space will be freed.
Do you want to continue [Y/n]? y
Get:1 http://us.archive.ubuntu.com/ubuntu/ oneiric/main unattended-upgrades all 0.73ubuntu1 [24.1 kB]
Fetched 24.1 kB in 0s (31.2 kB/s)
Preconfiguring packages ...
(Reading database ... 287206 files and directories currently installed.)
Removing flashplugin-downloader:i386 ...
Removing libasound2-plugins:i386 ...
Removing libpulse0:i386 ...
Removing libsndfile1:i386 ...
Removing libvorbisenc2:i386 ...
Removing libvorbis0a:i386 ...
Processing triggers for libc-bin ...
ldconfig deferred processing now taking place
(Reading database ... 287174 files and directories currently installed.)
Preparing to replace unattended-upgrades 0.73ubuntu1 (using .../unattended-upgrades_0.73ubuntu1_all.deb) ...
Checking for running unattended-upgrades:
Traceback (most recent call last):
File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module>
import apt_pkg
ImportError: No module named apt_pkg
invoke-rc.d: initscript unattended-upgrades, action "stop" failed.
dpkg: warning: subprocess old pre-removal script returned error exit status 1
dpkg - trying script from the new package instead ...
Checking for running unattended-upgrades:
Traceback (most recent call last):
File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module>
import apt_pkg
ImportError: No module named apt_pkg
invoke-rc.d: initscript unattended-upgrades, action "stop" failed.
dpkg: error processing /var/cache/apt/archives/unattended-upgrades_0.73ubuntu1_all.deb (--unpack):
subprocess new pre-removal script returned error exit status 1
update-rc.d: warning: unattended-upgrades start runlevel arguments (2 3 4 5) do not match LSB Default-Start values (none)
update-rc.d: warning: unattended-upgrades stop runlevel arguments (0 1 6) do not match LSB Default-Stop values (0 6)
Checking for running unattended-upgrades:
Traceback (most recent call last):
File "/usr/share/unattended-upgrades/unattended-upgrade-shutdown", line 27, in <module>
import apt_pkg
ImportError: No module named apt_pkg
invoke-rc.d: initscript unattended-upgrades, action "start" failed.
dpkg: error while cleaning up:
subprocess installed post-installation script returned error exit status 1
Errors were encountered while processing:
/var/cache/apt/archives/unattended-upgrades_0.73ubuntu1_all.deb
E: Sub-process /usr/bin/dpkg returned an error code (1)

Maybe I missed something basic, but I would appreciate pointers on solving the issue. Thanks