It sounds like a problem with the Search album template.
Could you have recently deleted an album template?
Go to the Publisher area of Backlight Settings and make sure you have a current album template chosen.
I think it needs to be a Pangolin album template (not Galleria, Theater)
Well right now, if you go to your site you’ll see an error:
So that needs to be fixed. In Backlight, go to Designer > Pages. Click on the name of the page you want for you home page. Click on Edit Properties. Set Index Page to Yes.
That’s not where you set the album template for the Search function. Go to Backlight > Admin > Settings. Scroll down to the Publisher area and look for Search Template.
Create a new Theater album using a Theater template set up for the Vegas slideshow presentation. Populate the album with images. You’ll probably also want to hide it from the album set.
In Backlight > Designer > Pages, edit the page you’ve chosen for your Index page.
In Design, go to the Insert Album tab and insert the Vegas slide show album you just created.