WordPress URL Problems After Change it

You can do this with 301 redirects. There is a nice easy plugin that will allow you to do this. https://wordpress.org/plugins/simple-301-redirects/ If you want to do it on a little lower level you can edit your .htaccess file with the structure you require. Yoast provides a easy to use generator available here: https://yoast.com/wp-content/permalink-helper.php

WordPress Permalinks 404 error

Could you try to replace .htaccess with the following? It looks like you’ve installed WordPress in a subfolder called solutions. # BEGIN WordPress RewriteEngine On RewriteBase /solutions/ RewriteRule ^index\.php$ – [L] RewriteCond %{REQUEST_FILENAME} !-f RewriteCond %{REQUEST_FILENAME} !-d RewriteRule . /solutions/index.php [L] # END WordPress