A service is a type of application (executable) that runs in the system background. Services usually provide core operating system features, such as Web serving, event logging, or file serving. Services can run without showing a user interface on the computer desktop. The SQL Server Database Engine, SQL Server Agent, and several other SQL Server components run as services. These services typically are started when the operating system starts. This depends on what is specified during setup; some services are not started by default.
This article describes the management of the various SQL Server services on your machine. Before you log in to an instance of SQL Server, you need to know how to start, stop, pause, resume, and restart an instance of SQL Server. After you are logged in, you can perform tasks such as administering the server or querying a database.
First of all make sure you have installed SQL Express in your system. Also, make sure you are the admin on the server. After install SQL Express Server database server will start automatically each time you start your computer by default.
Let’s start now, select start/All Programs/Microsoft SQL Server2005/Configuration Tools/SQL Server Configuration Manager. It should look like Figure 1.
And you will see the Window in Figure 2. You can see all started and stopped services.
To start or stop a service, select the service in the right pane and use the buttons in the toolbar to start or stop the service.
If you want change start mode of any service then Click on the property on that service and click on service tab. Then you will see this window. There are three start mode in a service.
I hope this will help.