Q: Because I kinda screwed it up with a failed attempt at installing and configuring Ubuntu, I now have unallocated space that I want to be with the other drive. Is there a way I can put it back? I originally had two C and D, so can I replace it back with D?
A: Yes you can, but it will delete everything on there most likely. You might want to use something like http://gparted.sourceforge.net/