They have probably left this account, so might as well give up on it. I'm just saying, it's been 3, soon to be 4, years since they have posted on here. If they are still on wattpad they either on a different account or are just being really sneaky.
I would choose them leaving the account due to the fact nobody has posted a message or a chapter of them changing accounts. Sure, there could be the possibility that they don't want people finding their old account, but I feel that they would have deleted the account by now.