Oh, well that makes quite a difference in a way, I mean, she should be laying. There really is not a lot you can do about laying. Every living thing that reproduces, varies quite a lot on how successful they are at it.
But you should check these things:
AArt - says to do a butt check. Look on here for pictures and technique. A laying hen has a wider spread between the pelvic bones. Then you know for sure if she is laying or not. The vent looks different between laying and non laying.
If she is laying - look for a hidden nest, or test the rest of your birds to see if someone else is not laying. Are you expecting the same count of eggs each day? Cause birds do skip a day every so often. I would not expect comet hens to skip too often.
Then you have to make a decision, do I keep her or not. In small flocks, sometimes it is important to have laying hens, sometimes it is not.
But truthfully, laying is a biological act, and there really is not much you can do, it is like how tall someone gets. As long as one has good food, water and shelter - that tends to produce good egg production, but if she is not laying with that, there really is nothing to add to make her lay.
Mrs K