Lethargic, tail down, not eating, not drinking

[casportpony]

With a bit of TLC this chicken eventually got better although we never figured out what was actually wrong with her. She's up to her usual antics of doing everything to escape the pen so she can eat plums in the garden. Only thing is she hasn't laid any eggs and she's been better for over 3 weeks. Is it likely that she'll never lay eggs now?