Help sorting out an old .aspx site

Hope someone can steer me right here.

Basically I've been asked to redo a site that was done ages ago in .aspx, which I don't really know anything about. (Although I am familiar with a bit of mySQL and PHP). As a brief history, someone I did another site for has bought out another local business, but for whatever reason, they didn't simply take on or transfer the existing hosting, but bought a new, almost identical domain.

So as a first step, I'm just trying to download the old site via FTP (I have the log in details), and upload it to the new domain.

I have downloaded it, but there was no index page, and when I uploaded the entire site, and pointed it to one of the .aspx pages I just got code rather than the page.

Anyway - this is the homepage of the old site :

http://www.cotswoldforge.com/

But when I navigate to the homepage of the new site, its a different page - presumably the aspx is doing something clever to create the page?

http://www.thecotswoldforge.com/

And a sample page on the old site is :

http://www.cotswoldforge.com/AboutUs.aspx

But looks like this where I've uploaded it :

http://www.thecotswoldforge.com/AboutUs.aspx

I'm starting to think its going to be easiest to start over, but if anyone could offer up any clues as to what's going on here, that would be much appreciated.

The odd thing is, I can't even see that the aspx is even doing anything particularly clever that the site really benefits from, except maybe a small database - but the navigation seems all a bit unintuitive to me.

Cheers.