Cant Set up, and now locked out of site

Hi There,

I just install supporter. when I activated it I got the following error
"The plugin does not have a valid header."

I tryed to uninstall by removing the folder and now my whole site is down and I am unable to acess any part of it only FTP and Cpanel SQL do I have acess to

I Know now where I whent worng I didnt take the time to notice the extra install instructions, and set up in different folder

But for now all I want is to get my site back up and showing, I have renamed the plugin folder but still no joy I have tryed fresh installs of the site I have even set up the config file to a new empty DB but still the system shows only a white page with a error
"Fatal error: Call to undefined function wp() in /home/rydalwuk/public_html/wp-blog-header.php on line 14"

I can understand where the problem is if I have re installed the whole site and have moved teh plugins folder and tryed to force it to re set up on a new DB ?

Please any help or pointers gratfuly recived since I am pulling my hair out here

Thanks In Advance

Nigel