Urgent Help - Application Starting Point no longer works after site's domain-name got changed

I got a site established for some time with a working domain and sub-domain

Today I've just registered a new domain and applied this new domain to the established site (by using "change domain" operation option)

As far as the primary domain name is concerned, its web-address, i.e. myNewDomain.com gets resolved correctly, i.e. the introduction homepage is being displayed as expected. I did not need to move a thing or any file/directory.

So far so good.

However, the myOldSubdomain.myNewDomain.com does not seem to work at all, where "myOldSubdomain" is my existing sub-domain name and also my existing directory - under which I stored my MVC application stuff) It has been chosen to be my "Application Starting Point" for a while. I know it is not working properly because instead of display a different homepage:

• the myOldSubdomain.myNewDomain.com URL gets mapped onto my default introduction webpage, i.e. myNewDomain.com (which i do not want)
  
  
• the http://www.myOldSubdomain.myNewDomain.com will show nothing on Google Chrome except the message "This site can't be reached" and that "www.myOldSubdomain.myNewDomain.com’s server IP address could not be found.

What I've done so far:

1. in the web.config's rerouting section, I have replaced any instances of my old domain (i.e. myOldDomain.info) to my new domain (i.e myNewDomain.com) This is the root web.config, or the site web.config if you will.
   
   
2. delete the old Application Starting Point and recreated the Application Starting Point, browsing to the same old directory, which bears the exact name of my old sub-domain, i.e. "myOldSubdomain" (this step does not help nor make any difference)

I don't know what I've been missing? Can someone please help bc need the site up and running by end of business day tomorrow, please help ASAP! Thank you.

 

Plz disregard, got it figured out.
Looks like after the new domain registration takes effect, one would have to create a "new" sub-domain name AND its corresponding directory to be set as App Starting Point. Then apply the same routing rule to this "new" sub-domain (if more than 1 sub-domain exist in one site) under which all files will be physically moved over from the "old" sub-domain folder. Yeah you have create and move things around : P and the old sub-domain is now obsolete.