Dashboard Wiget Order Plugin has taken my site offline …

Hi

I was just installing some WPMU plugins into my site and got as far as installing the Dashboard Widget Order plugin when it started displaying an: ‘The Dashboard Widget Order plugin is only compatible with WordPress Multisite.’ error message and won’t let me access any area of my site including the main site home page. I’ve looked in the plugins folder to see if I can delete the Dashboard Widget Order plugin but it doesn’t appear to be in there.

Please can you help asap as my site is currently offline?

Here’s the URL to my site:

http://webdesignfactory.co.uk/mana/