"Page not found" shows after publishing galleries.

Hello all!

I’m having some issues posting galleries. I was able to post them without having to create a gallery within the add media section, but it wasn’t showing all the pictures that I selected. So I tried to add a few plug-ins to help add all the pictures I wanted on each page. It looked fine when I previewed it but when I published it, it said page not found. So I removed the plug-ins and decided to go back to the way I was able to do it before, but not it’s not displaying any of my pictures when published even if though the preview shows it perfectly.

I’m not sure what the reason could be for it to not show up at all. I need some guidance please!!

Thanks!