Actually, just upgraded to 2.71 but here is my issue.
I was in the General Settings section and decided it would be nice if I made the header clickable back to my main site. So . . . I changed the WordPress address (URL) from http://mydomain.com/blog to simply http://mydomain.com
Now I can't login to http://mydomain.com/blog/wp-admin. I get a 404 error
The requested URL /wp-login.php was not found on this server.
Additionally, a 404 Not Found error was encountered while trying to use an ErrorDocument to handle the request.
When I go to my site via the control panel, all the files are there, and the blog shows up (minus the template).
How do I correct this?
I promise never to do this again.