All hens stopped laying!! Help!

[Brookwood Coop]

We have 7 hens, all of whom stopped laying 3 weeks ago. They are first year layers and were doing very well, and always laying in 2 of their 3 nesting boxes. They seem healthy and are acting completely normal. We’ve had a backyard coop for 5 years and have never experienced this! I’ve seen production drop off when the days get shorter, but something must be wrong here... any insight would help- Thanks!!
Also, we have a very large fenced run and have scoured every corner searching for any eggs!

 

[Horserider77364]

is it starting to get cold in your area? All my hens have stopped laying because its getting cold

 

[aart]

We have 7 hens, all of whom stopped laying 3 weeks ago. They are first year layers and were doing very well, and always laying in 2 of their 3 nesting boxes. They seem healthy and are acting completely normal. We’ve had a backyard coop for 5 years and have never experienced this! I’ve seen production drop off when the days get shorter, but something must be wrong here... any insight would help- Thanks!!
Also, we have a very large fenced run and have scoured every corner searching for any eggs!

How old are they in months?
Pullets do sometimes do slow/stop laying, and may even have a partial molt, their first fall/winter.

Might be time for an exam:
https://www.backyardchickens.com/articles/who-is-laying-and-who-is-not-butt-check.73309/

Then maybe.....
Free range birds sometimes need to be 'trained'(or re-trained) to lay in the coop nests, especially new layers. Leaving them locked in the coop/run for a week or so can help 'home' them to lay in the coop nests. Fake eggs/golf balls in the nests can help 'show' them were to lay. They can be confined to coop and maybe run 24/7 for a few days to a week, provided you have adequate space and ventilation, or confine them at least until mid to late afternoon. You help them create a new habit and they will usually stick with it. ..at least for a good while, then repeat as necessary.