ASP.Net MVC3 Html.PasswordFor does not populate

This is as designed. Passwords are not filled to prevent accidental resubmits, and to prevent the page from containing unencrypted passwords. Obviously the password was wrong to begin with if you're posting back the credentials.

In your case, you could create an extension that does input the data, or just use an HTML input of type password.

MVC protects you from doing something like this for a reason. You shouldn't actually be able to do this because the users password should not be stored unencrypted and unhashed. If your goal is to end end up on http://plaintextoffenders.com/ though, you can do something like:

<input type="password" name="Password" id="Password" value="@Model.Password" />

As described above, it is better to avoid doing this for security reason. if you still want to persist the password so that you proceed from where the current validation failed, you can use the HTML helper with html attribute parameter:

     Html.PasswordFor(x => x.Password, new { value = Model.Password})