I upgraded from 11.10 to 12.04 following the instructions here. https://help.ubuntu.com/community/PreciseUpgrades. But after the upgrade a lot of my image processing packages don't work some of their dependencies have been removed. Honestly there is not that much difference between 11.10 and 12.04. So please can someone tell me how to safely remove 12.04 and go back to 11.10 without losing documents, and source packages on my old Ubuntu. Thanks