If your Windows update is not working with an error 80072f8f, this usually means the computer's Date and time being way off.
Please make sure your date is correct:
Right-click on your Date and time (bottom right of taskbar) > click on the link "Change Date and time Settings" and correct the date/time. You may also try the "internet time" tab and update your date this way.
See also:
What is "Windows Update Error 80070103" ?What is "Windows Update error 800f020b" ?
