Next/Prev/Close buttons on Lightbox not showing

I am using the lightbox gallery. The images are showing fine but the next, previous and close buttons are showing as a missing image. I have recently moved all files from within a holding page folder to the top level of the site but these 3 images are still lining to within the folder – (…/old/wp-content/plugins/nextgen-gallery/…extgen/modules/lightbox/static/jquery.lightbox/lightbox-btn-close.gif.) I need to change this to …/wp-content/plugins/nextgen-gallery/…extgen/modules/lightbox/static/jquery.lightbox/lightbox-btn-close.gif but cant access the code.

Any help is appreciated.

Thanks.

https://www.ads-software.com/plugins/nextgen-gallery/