If you can see HTML and ASP pages  ok but not ASP.NET, that means IIS and
ASP.NET aren't in sync. Run the following from a command prompt.

aspnet_regiis.exe -i

That re-configures IIS registry settings for ASP.NET

That EXE is under the Windows folder. Might have to search to find exactly
which folder it's in, if your PATH doesn't include it.