How to add slider to show multiple view's product in a slider in commerce site of drupal 7?
you can achieve your requirement using views_slideshow module. 

Views Slideshow can be used to create a slideshow of any content (not just images) that can appear in a View.

News item slideshow (such as the title, image etc).

The Last X number of X submitted (images, videos, blog entries, forum posts, comments, testimonials, etc.).

Rotate any image, based on any filters you can apply in views.

Hottest new products for any ecommerce drupal site.

Rotate contact links, share links, etc.


Implementation :

Steps:

Enable view slideshow module.

Create a view using existing content type(ex-product).

View format: Slideshow

Add item for slideshow (such as the title, image etc).

For getting Next &amp; Previous link

Goto view slider settings 

Enable the controls as text.

It displays 'next','pause' and 'previous' link 

Later you change the css as per requirements.