This issue may be connected with SEO URLs settings on your WordPress website.

  1. Check whether your SEO permalinks are enabled under Settings-Permalinks. If they aren’t, choose the preferred URL structure and Save.
  2. Connect to your website via FTP and check for the .htaccess file in your WordPress root folder. If this file is missing, SEO permalinks won’t work.

To fix this issue. you can create an .htaccess file by yourself. Follow these steps:

  1. Create a file on your local computer (in NotePad or SimpleText), call it ‘1.htaccess’.
  2. Upload this file to the root folder of your WordPress via FTP.
  3. Rename ‘1.htaccess’ to ‘.htaccess’.
  4. Set the permissions for .htaccess file to 660 or 664
  5. Insert the following lines of code in your .htaccess: (works for 3.x WordPress versions)
# BEGIN WordPress

 RewriteEngine On
 RewriteBase /
 RewriteRule ^index\.php$ - [L]
 RewriteCond %{REQUEST_FILENAME} !-f
 RewriteCond %{REQUEST_FILENAME} !-d
 RewriteRule . /index.php [L]

 # END WordPress