I have made a presentation in PowerPoint with Slides and I have also created a video in export option in the menu but whenever i try to open that saved video files it wont work.
I also want to add some background audio to the video as well
I am trying this process in [questionable link removed] Package
You should background audio inside your PowerPoint presentation.
I had no troubles with exporting a 30-page presentation to video.mp4 file. What version of PP you did use? Where you got it from? Can you reduce your presentation to a generic five-page presentation, and if it does not work, to publish that file so we can try it as well?