Installed New Theme- White Screen on Every Page

(Please do not use your email openly anywhere in the web)

Simplify means this one ? http://wordpress.org/extend/themes/simplify

You can log in to your FTP and rename the folders by adding a dot ( . ) before the folder name to deactivate. Like :

For All Plugins -> plugins folder under wp-content, add a . before plugins -> .plugins
When you will remove the dot again by renaming, they will appear as deactivated plugins.

For themes – > Go to themes folder, add dot to specific themes except the default theme (to test).