Perhaps the voices in their heads are telling them not to lay...
But seriously, there are all sorts of factors influencing laying hens, physical, emotional, hormonal, environmental, & psychological. I've heard reports from other chicken keepers about their flocks "mysteriously" slowing/stopping production for a period of time, mine did the same a few months ago & I still don't know exactly why.
It seems the best you can do is try to address all the factors & concerns. The first thing is to rule out hidden nests & egg eating. Keep them confined so they'll lay in their nest boxes & check more frequently during the day to see if anyone is eating up the eggs.
Keep watch on their health & well-being, perhaps add some supplements like oyster shell, dairy, ACV, vitamins or electrolytes.
Make sure they're not getting too many treats so they're not eating enough of their layer ration.
Check for mites or worms.
Clean out & fluff up their nest boxes, add new & interesting nest eggs.
Offer them cash incentives. Make a sticker chart for them. Promise them a trip to Disney Land.
Hopefully their egg strike will end soon, before you have to actually *koff*koff* buy eggs at the store!
