1.Login Joomla in the administrator section.
2.Click the System menu, select Global Configuration.
3.Click Site, select Site Offline to Yes.
4.Select Offline Message to display a notice message.
5.Press Save & Close
6.Open a Joomla web page to view the results.
7.Login Joomla in the administrator section.
8.Click the System menu, select Global Configuration.
9.Click Site, select Site Offline to No.
10.Press Save & Close