this is a another problem i have with gallery field. this time my problem is when visitor click the thumbnail or title it goes to single page but my problem is my images are not showing please see the following codes.
Just to clarify, your images are not showing on the single page? That is most likely because of the code you have written. There is no need for a new WP_Query on this page as it is a single page. The global $post object is already setup.
I think you should read over the WP docs to get a better idea of coding WP themes before jumping into the deep end of ACF dev.