Show a 404 page if route not found in Laravel 5.1

I am trying to figure out to show 404 page not found if a route is not found. I followed many tutorials, but it doesn’t work. I have 404.blade.php in laravelresourcesviewserrors

Also in handler.php

public function render($request, Exception $e)
{
    if ($e instanceof TokenMismatchException) {
        // redirect to form an example of how i handle mine
        return redirect($request->fullUrl())->with(
            'csrf_error',
            "Opps! Seems you couldn't submit form for a longtime. Please try again"
        );
    }

    /*if ($e instanceof CustomException) {
        return response()->view('errors.404', [], 500);
    }*/

    if ($e instanceof SymfonyComponentHttpKernelExceptionNotFoundHttpException)
        return response(view('error.404'), 404);

    return parent::render($request, $e);
}

If I enter wrong URL in browser, it returns a blank page. I have

'debug' => env('APP_DEBUG', true),

in app.php.

Can anyone help me how to show a 404 page if route is not found? Thank you.

Answer

I recieved 500 errors instead of 404 errors. I solved the problem like this:

In the app/Exceptions/Handler.php file, there is a render function.

Replace the function with this function:

public function render($request, Exception $e)
{
    if ($this->isHttpException($e)) {
        switch ($e->getStatusCode()) {

            // not authorized
            case '403':
                return Response::view('errors.403',array(),403);
                break;

            // not found
            case '404':
                return Response::view('errors.404',array(),404);
                break;

            // internal error
            case '500':
                return Response::view('errors.500',array(),500);
                break;

            default:
                return $this->renderHttpException($e);
                break;
        }
    } else {
        return parent::render($request, $e);
    }
}

You can then use views that you save in views/errors/404.blade.php, and so on.