Web sites and Web applications depend on the availability of Internet Information Services (IIS) application pools. IIS application pools in turn depend on the Windows Process Activation Service (WAS). If WAS is not running or errors occur during the startup or shutdown of an application pool, Web sites and Web applications may not be available.
To resolve this problem you will need to debug the application and then restart the application pool.
To recover an application pool that has been disabled, follow these steps:
Correct any problems in the application that was running in the worker process. The application may have to be debugged and retested.
Restart the application pool.
To restart the application pool:
Click Start, click Control Panel, and then click Administrative Tools.
Right-clickInternet Information Services (IIS) Manager and select Run as administrator.
In the Connections pane, expand the computer node for the Web server and select the Application Pools folder underneath it.
In Features View, select the application pool you want to restart.
Right-click the application pool and select Start.
You can also use this link to restart the application pool:
Recycle Application Pool