Missing Application Pools Folder in IIS - Windows Server 2003

to get the application pools back to the IIS please follow the steps as mentioned below:

1. In IIS Manager, expand the local computer, right-click Web Sites, and then click Properties.
2. Click the Service tab, clear the Run WWW service in IIS 5.0 isolation mode check box, and then click OK.
3. To start the WWW service, click Yes when asked if you want to restart IIS now.