Recently I sold a puppy who after eight days ended up in the vets with parvo. Ive refunded her money to pay her vet bill. But none of the puppies at my home have showed any signs and its now 12 days after that puppy had left. Can just one pup in a litter get parvo. Im very confused as I thought it affected the whole lot any help with matter would be great. My puppies I have at home have now been vet checked and first vac given. I just want to know if the parvo is in my house or did it pick it up at hers.

It is hard to say, the incubation period (time from contraction to symptoms) is 1 - 2 weeks so you are right on the edge.

How long were they vaccinated before prior to selling?
Vaccinations take 14 days to be fully effective. It may be possible that the vaccinations hadn't fully 'kicked in' in that one puppy due to illness or a weaker immune system and they were unlucky enough to contract it, while the other puppies stayed protected.

My opinion is that the pup contracted it at the new owners home, it would be unlikely for one pup out of a whole litter to get parvo from the home, although you can play scenarios out in your head like the one above, they are unlikely.
However, if you sold before the 14 day vacc window then you did the right thing in refunding the money and I applaud you for that.

Did all the puppys get the parvo shoot it takes 14 days for it to kick in the puppy probably got it at her house because all the other puppys was not sick at your house that's all I got hope it gets better

None of the puppies were vacinated at the time I sold the puppy. She was meant to be doing this her self. The puppies at my house after her telling me her pup had got the virus. I then took my pups left to the vets for checking. They were parvo clear and the vet vacinated them there and then. The women is refusing to show me the vet bill now.?

The women was meant to be vacinating the dog herself. I now know that I will never let a puppy go until it is fully vacinated. And people will just have to wait for their puppies as I feel I should never of left it for her to do. The puppy did survive and is fit and well now.

I'm glad to hear the puppy is doing well, thank you for keeping us updated.
To cover yourself, puppies should always be vaccinated 2 weeks prior to selling.

Parvo treatment is usually quite expensive, but if caught early on the price drops as they require less care.
Just a theory but perhaps the vet bill was lower than what you refunded and she does not want you to know?
Whatever her reasons I would still say it is a good outcome overall.