My cat had a kitten at 4:30, today, she still, looks pregnant, she is comfortable,and she pants and pushes, but nothing comes out, my question is is she still in labour, and for how, long will this last

You need to get her to a vet. It's very possible that the kittens are too big to be passed naturally. If you don't get her to the vet, then her and any unborn babies will die.

When you take her to the vet, be sure to take her baby with you, too.

She could have a baby stuck, one that is too big, one that is trying to come out sideways. Try and GENTLY feel her tummy, if you can't feel it, it is probably stuck. Your cat and kittens will probably die if you don't get them to a vet ASAP!