I usually change the homepage for any computers that I fix up to load this page. I suggest their owners read the information available here (it may help them avoid another repair job), bookmark this page for future reference, and then reset their browser's homepage to whatever they prefer (in many browsers that can be done by dragging a link, or dragging the website icon from the address bar, onto the homepage button).
The above links point to pages with rather generic information, other parts of the computing section of my website have pages that are more specific to particular types of operating system, some of which have links below (or in the navigational table of contents, on the side).