On the Application server, I would search for and launch SQL Server Management Studio.
Once it opens, make sure Server Type is selected as “Database Engine”, “Authentication” type is is Windows Authentication and click on Connect.
Once you are into the studio, expand the “Databases” tab.
When you have found the Database you want to bring back online, right click on the database name, then click on tasks, then click on bring online
Once you have clicked on bring online, you should see the box below