Internet Information Services (IIS) Web sites that use HTTP rely on several important IIS components for their availability. The Windows Process Activation Service (WAS), the World Wide Publishing Service (W3SVC), the HTTP service, all must be running correctly. In addition, a properly running application pool must be available for the Web site’s applications. If any of these components is not functioning, the Web site will not be available.
Set a valid application pool
To configure a valid application pool for the Web site:
Click Start, click Control Panel, and then click Administrative Tools.
Right-click Internet Information Services (IIS) Manager and select Run as administrator.
In the Connections pane, select the Web site that you have to configure.
In the Actions pane, click Basic Settings... The Edit Site dialog box appears.
To the right of Application pool:, click the Select... button. The Select Application Pool dialog box appears.
In the Application Pool drop-down box, select a valid application pool for the Web site.
Click OK to close the Select Application Pool dialog box.
Click OK to close the Edit Site dialog box.
If the site is not already started, in the Actions pane, click Start to start the Web site.
You can also start the site using the link below:
Start Web Site