I wouldn't hold out much hope, in the past a few people have had items given to them which they'd 'lost' due to a system problem but in this case even if the logs exist ZOS' CS department have collapsed under the weight of tickets so even it seems unlikely you'll get a reply anytime soon.

If you want to try, best idea is to raise an in-game ticket using /HELP (if you can) or else open a ticket on the website here:

https://help.elderscrollsonline.com/app/ask/

if you do it in-game, make sure to sue /HELP and not /BUG, using /BUG will not get you a reply, ZOS make it clear that's simply to report bugs that you don't need any assistance with.

It sucks I know, I think many players have suffered something like this .. I lost a 'blue' fish due to a blatant bug and ZOS wouldn't credit me with it .. I'm afraid ZOS servers aren't the most reliable in the world even when not horribly overloaded like the console servers are right now.

I appreciate the kind words. I did do some research and found it was towards a trophy achievement to obtain a dye as opposed to a vanity pet which I had thought, so I'm not as upset. Just leaves me with a taste of vinegar in my mouth that the first item of this rarity to drop was sucked into the void. But, I did play EQOA and WoW so I wasn't expecting too much from the moderation team. Plus, when I logged back in the rollback had taken the gameplay back to a previous state to before I even had grabbed the quest which I was completing to kill said spiders to receive said drop, so the event itself probably doesn't exist in a log. Once again, thank you two.

I received a reply the following day from my ticket that was automated and had no information regarding what I asked. So, yea....tickets are pointless in this event.