q?=user login not working

Hi, we were testing our site and each time a new user would log on we would get the "user warning: duplicate entry blah blah ... " warning. I read through the help and saw that the sessions needed to be dumped which would log out all the current users but that seemed fine ... until I as admin was dumped out as well and now cannot get back in with the http:siteetc.com/q?=user login.

So where do I go and what code do I have to modify to manually turn the site back on?

Thanks so very much.