The service is unavailable

I am getting “The service is unavailable.” message when try to connect to my site… What could be the issue?

Might not be running.

Change the <system.web> section of your web.config to the following. This will send site error messages back to your browser and may show more detail on what is failing.

  <system.web>
    <customErrors mode="Off" />
  </customErrors>