General Settings URL issues

I have a client running an add-on domain on his hosting account. I installed WP and a theme on the account under the appropriate folder for his add-on domain.

Issue is I couldn’t get the URL’s to show up correctly…it always stayed on the main URL, regardless of what page you were on. Didn’t got to site.com/about.php, etc.

So, I modified some of the General Setting URL settings to see if anything changed by using a different file path. I actually can’t use the site now…

I need to change the URL settings back the way they were, but can’t even login now.

Is this a change that has to be made somewhere in the database now? Or, is it in a WP file that I can modify and FTP back up??? Or is there an easier solution.

Thank you