In the web using c# would be simple
System.Web.HttpUtility.HtmlDecode()
but now I am using a winform application and need to convert Html escape values whats the equivalent?
You can just reference the System.Web library and use it
If you add System.Web to your project references, then you should be able to use the HttpUtility.HtmlDecode method.
Just add a project reference to the System.Web dll and you should be able to use it.