Pigeon parents not returned to nest


We have a wood pigeon nest in our front tree and the baby looks to be about 11-13 days old by the feathers it has. For the past 2 days it appears that neither the male or female have returned to the nest. Previously one of them would be there nearly all the time and slowly they started to leave the nest for longer periods but one was always there evening and in the morning. However the past 2 days neither have been there in the evening or morning. Can anyone offer advice?

I don't want the baby to die.

Thanks in advance.