When access to WordPress, 404 Page Not Found error appear, it might caused by the Permalinks not configure well.
It has a method to overcome the issue.
Option 1: Correct the Permalink via the WordPress administrator dashboard.
1. Login to WordPress Dashboard,
2. From the left-hand pane, click Settings -> Permalinks (copy and save the setting to somewhere if you are using custom structure).
3. Select Default setting, save it.
4. Change back the previous setting, save it.
This will resolve the permalink issue.