Answer by user1362567 for How to roll back Ubuntu to a previous version?

You can do it manually.

First generate a list of what you have installed on your system. You can do this by typing the following in the terminal.

sudo dpkg --get-selections | grep '[[:space:]]install$' | \awk '{print $1}' > package_list

copy your /home and /etc folder to a backup media.

Re install ubuntu 10.04. Restore your backup (remember to set the correct premissions). Then run the following to reinstall all the program you had before.

cat package_list | xargs sudo apt-get install

Note that you might have to do some cleaning of the /etc and /home folder for incompatible settings.