Pages Not Found!

Have www.remarpro.com installed.
Long in page opens. Index page opens, but no theme is displayed, just text.
When I attempt to use dashboard, wp-admin, theme editor or plugin editor, they all return the same answer: Page Not Found!

Please inform how I can activate the opening page, with the default theme.
As soon as I have access to the Dashboard, I can get it working from there.

Thanks a million.

Jamaral