Media is missing

I have used Premier Rush to download 5 videos so far which have been fine. Now today I tried exporting a video (of which I was very proud of and excited about uploading) and it shows error message and media is missing. This is by doing it on my phone. I tried chopping the video and even making another with different videos. NONE of them are exporting and have the same message. When I go to media files, everything is there and opening fine. This is very frustrating and I don't know what to do next!