I was hoping that it was just a preview problem that would be fixed once I rendered it, but no, the final film turned out green too. I've tried restarting the computer too, but that did nothing.
The only saving grace is that the clips themselves in the media room are still normal, but all the ones on the timeline are green.
Can anyone give me some advice? I'd really hate to start all over again since I've put so much time into this. Thank you for your help.