iMovie Library disappeared UPDATED: FOUND.

So I was sharing a video when I got an "Error: RequestFrameAt returned: 3 for absolute frame: ###" message, so I went to this thread: https://discussions.apple.com/thread/251754895?page=1

to fix the issue.

I tried the first solution: holding down the Option and Command keys and selecting to delete preferences in the box that appears.

When my iMovie reopened, EVERY project was gone. I have since updated my computer in the thought this could help but they're still gone. Is there any way to recover my library?

I have a backup drive to retrieve all of my projects but one--the one I was working on today and attempting to share.

UPDATE:

• I went back into my computer and through some strange digging through my hard drive, I found an "iMovie Library" that re opened all of my projects into my iMovie again.