I suppose I could handle this with a bookmark, but this is the link that I can never find:
https://www.microsoft.com/en-us/software-download/windows10
Now it will be available when I am on someone else's computer.
I have found that the odds of a successful update improve when I run the Windows Update Troubleshooter first. You can find the update troubleshooter at this site:
https://support.microsoft.com/en-us/help/4027322/windows-update-troubleshooter
Download and run the troubleshooter against Windows Update. Allow the troubleshooter to fix any problems. If there are problems that aren't fixed, run the troubleshooter a 2nd time.