hello
when I try to put my user and password on manager section I will get Incorrect username or password entered! message , I didnt any changes in cpanel or modxcms at all
Be sure you’re using the username/pwd that you entered during the MODx install (not the cPanel or DB ones).
If that doesn’t help, see the "forgot password" item near the bottom of this page:
http://www.bobsguides.com/modx-newbie-faq.html.
You may have just forgotten the correct username/password, but be aware that someone may have hacked your site and changed the password. Even if the site looks normal, you should compare the index.php file in the site root with the original to see if there have been any suspicious changes and check the Manager logs to see if someone has changed the password lately (besides you).