As a new ubuntu user, I just make a mistaken. I've deleted a folder /var/lib/dpkg/ instead of /var/lib/dpkg/lock :) Now when I execute apt-get -f install then it will display error message: ... E: Cannot get debconf version. Is debconf installed? debconf: apt-extracttemplates failed: No such file or directory ... I've try this tutorial: http://people.adams.edu/~cdmiller/posts/Ubuntu-dpkg-recovery/ but still no luck. How can I fix this issue?