To ensure Web site and Web application isolation, Internet Information Services (IIS) application pools must be configured to have unique names and correctly configured identities. If errors occur during the configuration of an application pool, the application pool may not be available to serve the Web sites and Web applications that are assigned to it.
Stop and restart the application pool
Application pools occasionally have to be restarted in order to return to normal operation. Because application pools depend on the Windows Process Activation Service (WAS), you may have to restart WAS. If you restart WAS, you may also have to restart the World Wide Web Publishing Service (W3SVC), which depends on WAS.
To stop and start the application pool:
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, expand the server node and click Application Pools.
On the Application Pools page, select the application pool you want to start or stop.
In the Actions pane, do one of the following:
Click Stop to stop the application pool.
Click Start to start the application pool.
You can also restart the application pool using the link below:
Recycle Application Pool
To stop or restart WAS:
Open an elevated Command Prompt window. Click Start, point to All Programs, click Accessories, right-click Command Prompt, and then click Run as administrator.
At the command prompt, type net stop was /y.
At the command prompt, type net start was.
Start any other services that were stopped when WAS was shut down, including W3SVC.
To start the W3SVC:
Type net start w3svc.