I'm sorry sorry @john74, it must be so difficult not to be able to have contact with your kids. It cant make this time of year with Fathers' Day looming much fun.
I guess the only thing you can do is to keep trying, although then you run the risk of being accused of harassment I guess. I'd love to think if you kept trying, at least every now and then, your daughter would eventually speak to you. Would you have a better chance with your other kids? Then only other thing that I can think of that may work is maybe sending a message at the same time every week. It may show that you are trying and are dedicated to maintaining some sort of contact... just a random thought.
Not that it helps any now, but hopefully as your kids get older they will come to realise that you were/are trying to be a good father to them. I can only suggest at the point you're currently at you think about the things that are important to you.. the things worth living for. It sounds like that would be your kids. So while they are rejecting your attempts at contact now, there's always a chance they will come around. They may not realise it right now, but kids need their fathers around so keep trying and keep them in your mind and keep fighting for them. And in the meantime reach out to anyone you can to get you through this... your GP, crisis helplines, support groups, anyone that can help you through so that you will be there when hopefully your kids are more open to contact.
Take good care of yourself John, like I said your kids do need you, and in time they will see that, so don't let them think you've given up on them. Again, I'm so sorry for hat you're going through, I just can't imagine how difficult it must be! We're all here to listen and help however we can John.