Help! Someone! Anyone! Before I rip my hair out! I have watched over 50 YouTube tutorials today to try and fix this issue and NOTHING is working! I rendered this video originally a few days ago and after I did, I decided I wanted to make a few changes. When I re-rendered it a second time, a lot of my videos were black after render. When I went to look on my track, they are showing up white now and when I click on the video to preview it shows up black in the preview screen! I have went to options and unclicked the "close media files when not the active application. I have restarted Vegas 5 times. I don't know what else to do! I don't understand how it is suddenly not working!

Can anyone advise?