Unable to access dashboard/ wp-admin

Accidentally I edited both url’s (wordpress & blog adresses) to an unrecognisable format within the dashboard (Settings -> General).

from – http://thisismyblog.com

to – http://www.this.ismyblog.com

I then hit the save changes button without checking the pasted url. *I know, I know… Stupid*

Is there a possible chance i could edit this elsewhere to regain access to the dashboard?

Please help

Courtney