Debian – Half of the software is gone; any way to recover

Mandriva used to be the distribution with a nice and user-friendly package management system. See this page for more info.

It was ahead of its time when it got out, but I think nowadays that Ubuntu Software Centre is way beyond others.

You can get a list of all the packages you ever installed from the apt history files. These live under /var/log/apt/:

$ mkdir /tmp/apt_history
$ cp /var/log/apt/history.log* /tmp/apt_history
$ cd /tmp/apt_history
$ for archive in *.gz;do gunzip "$archive";done # Extract the logs
$ grep Commandline * | awk -F'install ' '/install/{print $NF}' | xargs

The final step will print a list of all the packages you installed manually, all on one line so you can easily pass them to apt-get. That said, removing all these packages in one shot is quite risky and will probably result in unrecoverable system breakage. Proceed with caution and make sure you know exactly what you're doing!