Unless you deleted them in an iCloud mistake they're probably not totally gone. This happened to me before with photos of that era. I wish I could exactly walk you through what to do, but it's been a while. In an update somewhere along the way there were actually multiple libraries created in my case. I was able to merge them back together
Always make sure you have a backup, too! Time Machine makes it easy.
@BE yeah, ill@go back through my backups and hopefully find them, but goddamn what a pain