HN is not the first line of support helpdesk for apple/facebook etc.
Enough FB engineers have identified themselves on HN that you might try approaching one of them but at the same time I think that you should first exhaust all regular avenues.
Whatever you do make sure that the machine that the data was on gets powered down in case there is still retrievable data on the drive. Likely the photos are all still there, they're just no longer linked. You may have a problem figuring out what is what. Search for 'photo recovery software' for some tools that may help with this.
You may have to move the drive to another machine to get at it but that would have to be in read only mode. Do not write to the disk or even mount it in r/w mode until you have retrieved all the data that you can get.