I'm having the same problem with some of my hens.  I have 7.  The two cream legbars were really prolific egg layers starting when they were about 6 months old.  That lasted a few months, but now they have both stopped laying completely.  They had fowl pox, so I understood that was probably making them stop, but now they seem to have been healthy for about a week.  I found one blue egg hidden in the garden a week ago, but that's it.  They seem completely normal and healthy, except their combs are slightly lighter than normal. They aren't molting near as I can tell. Any ideas on these?
My leghorn & one of my buffs continued to lay throughout the fowl pox.  The leghorn lays almost daily.  The Buff lays about 5 eggs a week.
The other buff was brooding when all that went on, so she had a mild case of pox, but wasn't laying because of brooding.  I've just started getting a few speckled brown eggs.  I know that isn't common for buffs (my other one lays smooth brown eggs), but I think they are coming from her.  They're only every 4 days or so.  I'm hoping she picks up to her normal pace soon.
Another hen (Columbian Wyandotte) is possibly getting old.. I don't know what age she was when we got her in 2011.  She's sweet, though, and gets along with everyone.  She's molting too.
The last one is a golden comet.  She just joined the flock two weeks ago, and had not only been an only chicken her whole life (one year they said), but she apparently also lived inside the house.  At night she literally scratches the glass door to come in, and she's only made it to the coop for bed twice without us helping her.  I don't think she is laying and when she does, it will likely not be in the coop.  Poor bugger.
All in, I'm having a variety of problems, but they all seem fairly normal and understandable except for the legbars.
Ideas?