Unable to open site

Dear Sir,

I recently found my site https://blog.pastace.com is not opened and found blog.pastace.com?is currently unable to handle this request.-HTTP ERROR 500. Also not able to login admin page, and “403– Forbidden-Access to this resource on the server is denied!”

I tried to check from file manager-Public_html-Blog…but its found empty.

Kindly guide how to restore site working.

The page I need help with: [log in to see the link]