I have grown very attached to this guinea. She came here 3 years ago with a mate and lost him/her,  don’t know which it is. I lost my husband last year too. I can’t believe how dumb these birds are, but they are funny. The neighbors house she’s at don’t like her so go figure. She is under a roof and drinking eaves water, but no food. They say lone Guinea will not survive well it’s been over a
		
		
	 
They can survive in the cold, but not free of consequences.  Frostbite is a very real issue, as is hypothermia and dehydration.
 She must be getting food somehow, probably litter in the same gutter she's drinking from. Most likely something frightened her in the shed causing her to abandon it, whether a furry predator or a snake.
If she's under a roof, she's found shelter to keep her dry; that's significant in survival.They can tolerate cold, but not wet and cold.
  With their eyes on the sides of their head, the have monocular vision, meaning they can only see out of one eye at a time. This is great for scanning large areas at a time with  sharp detail.
  Because no one has ever got a straight answer from a guinea on the subject, I will only say that it *is suspected* that when winter days are cloudy and there's snow or frost on the ground, this monocular vision works against them. Everything is white, so determining up and down becomes frightening. Hence the pathway R2 mentioned.
  I've also played recordings of guineas calling to coax them down.  Nothing is guaranteed every time, but soometimes they work.
Make sure the shed is safe from predators, & if she returns to it, keep her lock in for a few weeks so she learns this is home. That way she'll return to it nightly on her own so you can close her in for her safety.  In addition to monocular vision, they can't see in the dark, so a guinea sleeping outside is easy prey.