IIS 5.1 shows directory listing instead of running web application

I have a mvc web application, previously it was running, I don't know what I did, but suddenly web sites in IIS stopped working and I got some kind of hexadecimal error, the problem was port 80 was being used by some other application, I 开发者_StackOverflow社区changed the IIS to use port 90 for web sites, but then my mvc application has stopped working with IIS, and IIS now shows directory listing of my mvc web application

what to do?

You may check the following guide about deploying ASP.NET MVC applications on IIS. Also if you are using extensionless URLs make sure you have a wildcard mapping for the aspnet_isapi.dll.