NO ADMIN- white screen - 1.5.2.1

Hello

i tried to install the facebook ecommerace browser app
http://www.opencart.com/index.php?route ... load_id=22

and crashed and burned.

Baiscally uploaded all the local files from my computer but not the config.php

when i have gone to sign in the admin file is there. but when i put in my password there is no back end. just shows a white screen.


any ideas folks.

my webhost has tried to do a restore from before the problem but not worked.
i have a opencart backup from the other day but i cant get into admin to fix it