Updates have made this issue resolved.
I have great news! I figured out what the problem was. It turned out that I had an plugin called Rename wp-login.php. I deactivated it and now everything works.
Thanks for getting back to me. I managed to disable iThemes.
This is my website: http://planthard.com/
Let me know what you find out.
Is anyone else having this problem? Is it because of the update from WordPress?