why the validation does not return form with input value

I am trying to return back the form with the value of by use. But it is not working .Please help

        $rules = [
            'name' => 'required',
            'subject' => 'required',
            'purpose' => 'required',
            'sender_email' => 'required|email',
            'sender_name' => 'required',
           
        ];
        $messages = [
            'name.required' => 'The Name field is required',
     
        ];
        $validator = Validator::make($request->all(), $rules, $messages);
        if ($validator->fails()) {
            return redirect()->back()->withErrors($validator)->withInput();
        }