Converted file to mp4 but can't open it - HELP!!

Hello, I just recorded a whole presentation, waited until it converted to .mp4, it successfully converted, but as I'm trying to open it I can't open it ANYWHERE. Tried opening it on my Acer - CAN'T; tried uploading it to Drive - CAN'T OPEN IT. I'm desperate because I need that recording and I can't open it anywhere from any platform, what on Earth could be the problem?? Thanks!