I accidentally threw my Christmas Mission book in lava, while clearing out items at around 6:11 on 12/2/19 I was told by a trainee (KarmaEchoes), because no Moderators were on at the time, to post a thread on Bug reports or somewhere else on Contact Moderators Forum. My in-game username is TheGoldenMiner7 I hope you can resolve my issue
As this was a player mistake, I wouldnt say that this can be fixed. This isn't a bug, and if you wish to (try) and get your mission book back, you can contact kiri