Linux.com has made a guide to support DebianGNU/Linux users when apt-get doesn't quite do the job.
You can read the description of apt-get and what to do here at Linux.com
A short bit of it:
One case in which you have limited options for recovering the system is when you are installing unofficial .deb packages from a third party, instead of from a Debian-approved source. Although more free and open source software (FOSS) projects provide Debian packages than they did five years ago, too often they build them without dependencies calculated. That leaves users in the same dependency hell that RPM users had to endure in the bad old days before Yum and apt4rpm.