How to reset things to their default, post-installation state?

[Patrick Doyle]

I've been playing with a number of different things on my Mythbuntu
box (ALSA drivers, proprietary ATI video drivers, etc...) and have not
had a whole lot of success getting things to work.  At this point, I
would like to just wipe the disk clean and start again.

But I figured I'd take the opportunity to ask if there is a different
way to achieve the same effect.  Is there some apt/aptitude/dpkg
command that will verify the files on my system against those in the
official Ubuntu packages and replace them (and/or inform me) if they
are different?  Basically, I am looking for something like

$ apt-get dist-verify

As I said, I'll probably just wipe the disk and start anew, possibly
having learned a thing or two from everything I've tried.

--wpd