I suddenly just lost my Origami Dragon, but I didn’t sell it or anything. Where did it go?

Hi and welocme to forum
you may want to send a support ticket to sp about it
https://forums.socialpointgames.com/topic/80/how-to-report-game-problems-to-support

Have you checked to the dragonarium, used in towers, for breeding, in storage? If you still cannot find it, submit a ticket to support.