Well I upgraded to Version: 3.6.6 today and shortly after my main page went blank along with all top menu items. I can still access like k2 area of site but nothing else.

Soooo i disabled joomsef and it still didn't fix come back in 3 different browsers. I even disabled seo in joomla and nothing... The only time i get a home page is if I set the site offline then i get the joomla offline page icon.

Does anyone have a clue if joomsef could have changed a core file when it upgraded?

i have Version 1.5.18 joomla installed

Hello,

JoomSEF does not change any core files.
Enable the error reporting on your server, so there is the underlying error shown instead of the blank page, and post us the error please.

Best regards,
ARTIO Support Team