iMovie vanished and cannot open imovieevent file backup
I have been working for hours on a new iMovie project but there were issues with videos that wouldn't play once placed in the timeline. Following previous advice found in the Community, I tried to quit iMovie to reopen with control+option and delete preferences, but had to Force Quit because there was a message "iMovie must complete other tasks before performing this operation" (left it alone for a couple of hours and still got the same message). On opening iMovie, as advised (with control+option), I find that the new project has vanished. I have found a Backup.imovieevent and a CurrentVersion.imovieevent in the Library with Finder (using "Show Package Contents"), but these will not open in iMovie.
Now, if iMovie cannot open an imovieevent file, then how do I access it???
HELP!
Catarina
PS: It's my daughter's 18th birthday and this movie was to be shown in the party tonight...
MacBook Pro 13″, macOS 13.4