There are many reasons why hens don't lay. Some are disease, poor nutrition, not enough light, etc. Have you done anything different lately to unsettle them? A change in their lifestyle can cause hens to stop or not lay also. As will a change in the weather.
Have you looked around carefully and made sure they aren't hiding a nest of eggs from you? I remember once years ago one of my earliest flocks seemed to never lay. It was getting ridiculous at 35 weeks and not one single egg. When deeping cleaning the hen house in a corner hard to reach I found a clutch of over 200 eggs they had BURIED! The hid them from me!
Have you tried supplementing their ration with some kitchen scraps - yogurt, rice, meat, veggies, bread and add free choice oyster shells. You could also feed them treats of meal worms and such to boost their nutrients. You might even try chopping up a few hard boiled eggs as a treat. Just in case there is something missing in their diet that is hendering the production of eggs adding things to their diet might stimulate them. I do not give my chickens ration as their main source of food. I use the ration as the supplement. They get lots of bugs and grass, most kitchen scraps, lots of vegetables and good breads (I get it free from the grocery store bread delivery lady when she is restocking the bread shelves otherwise she throws it away - what a waste!). I have goats and the hens also get yogurt and whey and any milk products that perhaps don't turn out exactly right. They have a very broad and wide diet.
How much light are they getting? I would suggest adding a 40 watt light to the hen house. Using a timer switch have the light come on in the early morning as opposed to adding light in the evening - the birds need to roost when the sun goes down, the morning light is just better for them. 14 hours of light is the general recommendation.
Something else I would suggest is check frequently to make sure the hens aren't eating eggs themselves.
Also is there a chance there is an egg eating predator lurking in the hen house? Like a snake?
There are so many reasons not to have eggs. My newest layers are 19 weeks and I am waiting for my eggs, too! But like us women the hens have their own cycle and maybe they just haven't matured to the point they are ready to lay. Give them a little more time and perhaps try some of the suggestion.
We all will be watching for the post with your first egg!
