I was messing with the htaccess file today. I have a couple of URL rewrites and then I put some code to close the site down to all users except for my ip address and redirect them to a site down page.
I have no idea what I did but I cannot access my site through just www.mysite.com.
You might benefit from reading the mod_rewrite tutorial linked in my signature as it contains explanations and sample code. It’s helped may members and should help you, too.
For what it’s worth, I copy/pasted your htaccess, and as long as my DirectoryIndex was set to index.php, it worked just fine. There may be something else going on that we haven’t seen.
It’s definitely in your interest to start using a version control system, such as Git. That way you’ll always know what you did and can always revert to an earlier version.