This article will help you to understand Error 404 cannot find the page.
Error 404 is a client mistake, either because you typed the URL incorrectly or the page has been moved or removed from the website and you should have known. Error 404 is generated by your server when a requested URL is not found. Also, it is possible if a website has moved a page or resource but did so without redirecting the old URL to the new one.
You can reset the permalink array by going to the permalinks tab in wp-admin and simply re-saving the permalink structure. Navigate to: WordPress Dashboard → Settings → Permalinks: Click “Save Changes” Test your URL. If the 404 goes away, something caused an issue with your permalink structure and this fixed it. Often the quick fix is enough to correct your 404 issues.