You have to build a time machine
I'd like to 'go back in time', before I messed up my installation. How can I do this?
Some terminal commands that may help:
sudo dpkg --configure -a
sudo apt-get -f install
sudo apt-get autoremove
sudo apt-get clean
sudo apt-get update
Another thought: If you like to do a lot of playing around and don't want to bork your system, consider VirtualBox. There is a learning curve, but in the end you will have that "time machine"