This problem usually results from the default menu item having been deleted. Log-in to your site's Joomla administrator. Then click on "Menus". Check the menu names in the drop-down list. One of the menus must have an asterisk following the name thus indicating it is the defaul menu. If none of the menu names have an asterisk, you must choose one to be the default. Click on the chosen menu name. Click the checkbox next to a menu item then click the "Default" icon (a gold star) near the top right of the page. This should place a gold star in the "Default" column for the menu item you selected. This will make that menu item the default, or home page for you site. Try viewing your site to verify proper operation.
This is an unusual condition. Joomla does not provide a way to delete or unpublish the default menu item in order to prevent just this occurance. Please submit a support ticket so our technicians can research the issue further. Please include the exact error message you saw when trying to access your web site. Remember you must login to the Client Area before you can submit a support ticket.
