How do i downgrade ubuntu ppc ?

[Bobby_Z]

Hello, my name is bobby , I Am new to apple computers, as well as Ubuntu , I have an old PowerBook g4 15inch aluminum , and I recently was able to install Ubuntu 12.04 on it , as apples O.S compatible with that PowerBook would be useless considering apple's stupid specific O.S requirement for every app , anyways lol not important my reason for this post is my sound wasn't working I thought upgrading it to 14.04 would fix the sound, So out of my own stupidity I tried upgrading to 14.04 , ignoring the graphics warning, I just figured I could insert 12.04 install disc back in & reformat/reinstall if something went wrong but when I go to boot disc its like YaBoot is skipping the disc I have tried booting from open firmware , pressing c , booting from options boot menu & it just opens the first YaBoot screen, I press c at that screen & it loads the same screen again , I am stuck in a ****** loop. I realize its my own fault but was hoping someone would know what I should do or if there is nothing I can do. Anyways as I said I Am new to this so this so any feedback is greatly appreciated, thank you for reading.

[Bobby_Z]

lol hello, this is bobby again, I figured it out I was using the desktop iso soon as I used the alternate iso disc booted up fine im back with 12.04, minus the sound but im sure there is a less problematic solution, so as it turns out I am still in need of help so if anyone can save me time again it would be greatly appreciated, thanks again for reading

[grahammechanical]

Just to be clear, because your posts are not that clear, you have installed using the Ubuntu 12.04 alternate ISO image? As I understand things, with the alternate ISO image we tell the installer which bits and pieces to install. Did you install Ubuntu desktop? It could be that an audio component was not installed. Do you have Ubuntu Software Centre or Synaptic Package Manager installed. If so, then search for pulseaudio. It is the sound server used in Ubuntu. See if it is installed.

Regards.