[Andrew4613]

I went down to collect the eggs yesterday and discovered one of my girls sat down and unable to move or put any weight on her legsI've inspected her legs and toes and can't see any cuts. She is eating and drinking within her range - any ideas what may be wrong with her!

[compostqueen]

Have you got her outside to see if she'll walk.  Tempt her with a bit of food out of her range and see if she'll attempt to walk towards you.  If not then there's something amiss. You could rest her up and hope she'll be all right in the morning. If not, I'd seek veterinary help

If she's a hybrid, was she vaccinated when you got her? 

[ANHBUC]

What age is your hen?  Young birds can suffer with slipped Achilles tendons.  You will probably be better taking her to a vet as she will be unable to stand to poo or lay an egg if she is a layer.  Make sure you keep her clean if she soils herself as she can suffer from fly strike.