$ sudo aptitude autoclean

$ sudo apt-get update

W: Failed to fetch
http://www.linuxtrack.eu/repositories/ubuntu/dists/precise/main/source/Sources
404  Not Found

W: Failed to fetch
http://www.linuxtrack.eu/repositories/ubuntu/dists/precise/main/binary-amd64/Packages
404  Not Found

W: Failed to fetch
http://www.linuxtrack.eu/repositories/ubuntu/dists/precise/main/binary-i386/Packages
404  Not Found

E: Some index files failed to download. They have been ignored, or old
ones used instead.

dpkg: error processing package linux-image-extra-3.19.0-65-generic (--configure):
 package linux-image-extra-3.19.0-65-generic is not ready for configuration
 cannot configure (current status `half-installed')
Errors were encountered while processing:
 linux-image-extra-3.19.0-65-generic
E: Sub-process /usr/bin/dpkg returned an error code (1)

$ sudo dpkg --clear-avail
$ sudo dpkg --configure -a