Cannot Un-redirect WordPress

I used site A to develop a site. Once running, I transferred it to site B by first copying all of the files to a directory called “old” then redirected the 2 files in the settings –> general section to point to the new site and copying those to a file called “new”

The problem is that the original site (site A) – even though I changed it back – continues to redirect to site B. I checked the config.php file, but it seems correct.

Even if I access the original site, when I click a menu, it redirects to a non-existing page on site B. Very frustrating.

What did I do wrong. I cleared all cookies and browser history as well.