URL changed; blog doesn’t work

Not positive which version of WP involved as I am updating for a friend’s account. Tried to change the address of the blog and moved the files to a new directory. Everything should have been fine except the hosting was taking time to respond, so I ignorantly added the extension “index.php” to the URL, URI addresses to see if that would allow the page to work. Now the blog displays in basic HTML; login doesn’t work and only returns to the index page. Since I can’t login and access the dashboard or any administrative area, I can’t edit the addresses to fix the problem. Is there any way to salvage this situation?