Log off administrator

Drupal:6.9
Wamp

Hi I was trying to modify a module; so I turn off the web site for (site maintenance). Than I went to locahost to see what it looks like. but nothing have change; it supposed to write : Guinsly's Website is currently under maintenance....

So I log off as administrator so now I could see the message: Guinsly's Website is curren.....

??????Now how can I go back and log in as administrator to be able to turn on my site??????

I made a back-up of everything (database & sql) before I turn it off.

Also I don't have a real website( the website it's on my Computer) I'm trying to learn Drupal with a book.