[Roba690]

One of my chickens went missing in the woods behind my house, since then another hen has become very quiet, she still eating and drinking, her  comb has gone floppy and she seems to just sit around and just grump rather than explore the garden

Any advice would be greatful cheers

[ANHBUC]

How old is she Roba690 and is she still laying?

She could be just missing her pal or had a fright but there could be an underlying problem with her health and just a coincidence in the timing.  Best to check her over, has she been wormed recently, check for sour/impacted crop, lice, egg bound etc.   

[Roba690]

Unfortunate events today, our chicken died, check all our others and they seem fine so just gonna keep a eye on them

[jhub]

Oh so sorry.
Chickens 'hide' illness so when they do show symptoms they can deteriorate very quickly and often it's  too late for successful intervention. It's very upsetting.