Gallery is now a slideshow

We have had two Hot Joomla galleries up and running well on our site for a couple of years. One of these is [url=http://http://www.thpclaos.com/index.php?option=com_content&view=article&id=91&Itemid=287&lang=en]here[/url]. I today tried to add a [url=http://http://www.thpclaos.com/index.php?option=com_content&view=article&id=91&Itemid=287&lang=en]third[/url] but it displays as a slideshow - and not all photos uploaded to the gallery will display. I have followed the same procedure as with the other two galleries, which display all the uploaded photos on one page. Why the difference and how can I fix it so it works as the other galleries do?

That gallery creates folder /thumbnails under folder where you put images. If that folder became not writable by website it will not be able to create them.
Check CHMOD of that folder. You can also just create thumbnails your self respecting name convention and put them there

Many thanks for looking into this. I have reduced the resolution of all photos and they now all display. However, the gallery still displays as a slideshow - like carousel - and not how my other galleries display, with all photos visible on one page. Settings are the same on these pages! I attach screenshots to illustrate.

I think you wanted to use hot photogallery plugin ( demo.hotjoomlatemplates.com/test/hot-photo-gallery-plugin ) , instead you took module

Thanks. I've fixed the problem. It needed a link to the image folder on the article page. e.g. {gallery}Image2015/gallery3{/gallery}