One of my posts says "page not found" after changing permalinks

What on earth?
Here is my site

http://www.getgreencoffeebeanmax.org

And one of my posts says page not found.

I checked my .htaccess and this is what it says:

# BEGIN WordPress
<IfModule mod_rewrite.c>
RewriteEngine On
RewriteBase /
RewriteRule ^index\.php$ – [L]
RewriteCond %{REQUEST_FILENAME} !-f
RewriteCond %{REQUEST_FILENAME} !-d
RewriteRule . /index.php [L]
</IfModule>

# END WordPress

This is the page that isn’t found:http://getgreencoffeebeanmax.org/green-coffee-bean-max-and-weight-loss/

(It absolutely IS there)

Can anyone help me, I’m yanking hairs out. 🙁

It is the permalinks causing this as the page is fine when I change it back.. I need the permalinks to be %postname% so desperate to fix this. If anyone can help?