I am making a video for my YouTube channel, using only picture files, mp4 files and the in-software narration tool, and I started to work on the video and when I load the project, it re-loads all of the files and says that the mp4 files are corrupted, I have not moved them/deleted them and I've used the help already on the site but it doesn't work, I've restarted Movie Maker, I've restarted my computer, I've saved it and that just made it worse. I've worked very hard on the video and I don't want to have to start again for no reason. Please help.