A 404 error code (and broken hyperlinks) throw many people for a loop, but once you understand what they are, they are easy to fix. First, a 404 error code appears when you have a broken link on your page. This generally occurs if you have deleted a page, renamed a page, forgot to publish a page, or have your home page named something other than "index", but the hyper-link is still trying to direct the visitor to that page.
1) First take note of the actual page name you are trying to link to.
2) Next from the link List select the link that is broken, then click the Edit Link button
3) The following window will appear. Make sure the spelling is exactly the same as the page you are linking to.
4) If the spelling does not match you can guarantee a correct link by clicking the browse button in the previous window, then scrolling down and selecting the correct page from the list of pages as shown below.
5) After you publish the page, the link should be fixed. You can verify this by looking at the URL in your browser (published site) to make sure the URL matches the page name.