Hen losing feathers but not growing back

[Top Rooster]

So ove the past year or so I have had 2 red sexlink hens who are amazing layers one of them has lost lots of feathers but she is not molting she just lost them over time and for some reason they haven't grown back I don't know why it makes her look like quite the rough hen. She eats and drinks fine, she doesn't seem to be depressed or anything, I'm just wondering why she hasn't grown her feathers back is it some sort of disease? Will she die? Will she ever grow feathers back? Keep in mind she hasn't all of a sudden lost the feathers she has lost them slowly over the year

 

[Wyorp Rock]

So ove the past year or so I have had 2 red sexlink hens who are amazing layers one of them has lost lots of feathers but she is not molting she just lost them over time and for some reason they haven't grown back I don't know why it makes her look like quite the rough hen. She eats and drinks fine, she doesn't seem to be depressed or anything, I'm just wondering why she hasn't grown her feathers back is it some sort of disease? Will she die? Will she ever grow feathers back? Keep in mind she hasn't all of a sudden lost the feathers she has lost them slowly over the year

Do you have a rooster?

If you have a rooster, the wing (shoulder) area that is exposed is most likely due to treading (mounting). I see broken feathers there as well.
Some of your other hens may be plucking/picking out some of her feathers as well.

Check her over for signs of lice/mites and treat accordingly.

Feathers that are broken/damaged generally won't grown back until it's time for her to molt. Then she will have pin feathers forming that will push out the broken feather shafts and replace them with new ones.

Observe your flock especially at roosting time to see if there is any picking.

 

[Top Rooster]

Our rooster is fairly young and he has only mounted her once because she is above him in the pecking order due to a fight that she won but in general she is the boss of the majority of hens except for a few who aren't aggressive