how to give enable and disable for @html.textbox in controller in mvc3.

The disable property isn't true \ false, but should just read as disabled....e.g

@Html.TextBox("txtIden1", new { disabled="disabled" })

You don't set this in a controller, your controller is responsible for returning a model to the view that dictates how it should be rendered. So, in your controller method

// Your model
public class SomeModel 
{
    public string SomeName {get; set;}
    public bool FieldIsDisabled {get; set;}    
}

// Your controller action
public ActionResult GetMyModel()
{
    var model = new SomeModel
    {
        SomeName = "Test", 
        FieldIsDiabled = true // would actually be some logic to determine this...
    }

   return View(model);
}

// Your view page

@model SomeModel
@{
    ViewBag.Title = "Home Page";
}


@Html.TextBoxFor(model => model.SomeName, model.FieldIsDiabled ? (object)new { disabled="disabled" } : new {})