"I downloaded to a stick". That's not the right thing to do. You must use the Windows Media Creation Tool (or Rufus, although I never used that myself) to make a bootable stick out of the .iso you downloaded.
And then, if you can't run the setup.exe from that USB-stick in your own (corrupted?) Windows, you boot from that USB stick to run it in a clean OS.
What exactly do you mean with "downloaded [from a stick] onto my PC"? Downloading is just copying a file from a server on Internet to a hard disk or USB stick on your PC, and not running it. And downloading certainly is not from a stick.
Very sorry for starting another thread on same topic but I am using someone else's laptop to help to sort out my own and this laptop is also having problems - going very slow, etc. I tried to press the button to answer on original thread but nothing happens.
Grif thank you for your response. I'm not having much joy. I bought an 8gb USB stick and downloaded windows 10 twice but each time when it gets to 99% it stops and says interrupted. When I check on the stick it says 'partial download'. So I then found what I think is the right network adapter to download to try and get the internet back on my laptop so I can download directly to it. I downloaded that to a stick. When I try to download it onto my PC it says that it 'cannot install in safe mode' or something like that.
I really don't know what to do. Is there anything else I can try?