Fix my wordpress site

I need someone to fix my wordpress site. There is zero designing necessary. I have made a mistake that I don't know how to undo. 1. Under the general settings of my site, I changed the url from "http:" to "www." After that, I lost connection with my database. 2. I have a issue with a theme feature that will not function properly. I know what to do, I just don't know how to do it. I expect this to be a very quick job. I just need someone who can do it immediately. Thanks so much.