WP at the wrong place… with a twist.

I had installed WordPress at http://www.mydomain.com, and everything was working smoothly. But then, I had a created an index.htm page with a message, so that that would be what visitors would see while I worked on customizing WordPress, etc.

Right now, the index pages aren’t a problem – I simply renamed index.htm to index.html and now that message shows up, rather than the WordPress index.php. The problem is that, while I was trying to get to that fix, I accidentally fiddled around with the location of WordPress, and changed it to http://www.mydomain.com/index.php (in both spots). That was a completely unintelligent move on my part, I realize. Now, I can’t even change that to http://www.mydomain.com again.

Is there anything I could do besides reinstall WordPress?
I’ve found many topics like http://wordpress.org/support/topic/16178, but my problem seems to be different. If I missed any that already answered my question, I’m sorry! ^^;;

Thank you so much for your time! Any help would be greatly appreciated.