Maintenance mode completely cuts off the front-end of your site from public view. Unfortunately, this also includes administrators, too.

You can, however, still get to your dashboard. Simple go to:

yourwebsite.com/dashboard

From there, you can still access your dashboard.

Hope this helps?

There is an add-on in the market place that lets you edit the site in maintenance mode - it also makes it easy to put up a custom "under maintenance" page when activated. Just search for 'maintenance' in the marketplace.

But like what growthcurve has suggested, you can access the dashboard and turn it off by typinghttp://www.yoursite.com/dashboard

If you are working on a local server with WAMP or MAMP you will need to type in localhost/yourprojectname/index.php/dashboard (i.e put 'index.php/' then dashboard after.

Hope this helps!