I'm very mad about this topic. I have had about 3 cats and they all have despawned. I spend my hard-earned rupees on ocelot eggs and they are no use! Is this the Server or what?
Because Ocelots are different from most mobs they will despawn if not tamed and not watched for a while. Did you tame them before they despawned or no?
The only thing I found to work for ocelots was to tame them as kittens, keep them seated at all times (except when breeding) and to put them in an underground pen with a roof and a water surround like the one discussed in this thread: http://empireminecraft.com/threads/vanishing-sheep.4978/ Good luck, and if you need a couple of eggs to get started again, let me know