It’s Hard to find why its happen without seeing your installation process. But this may help you:
- You can reinstall your project
-
By mistake you forget your admin URL; You can see/change admin URL from
app/etc/env.php at line no 5.
return array ( 'backend' => array ( 'frontName' => 'admin_q76xvk', ),
-
Clean cache/reindexing and delete
var/cache
,var/page_cache
folder. -
Make change in
.htaccess
(Just copy this filepub/.htaccess
to magento root folder)
OTHER WAYs
https://www.mageplaza.com/kb/magento-2-404-page-not-found.html
https://magento.stackexchange.com/questions/133679/404-not-found-error-for-admin-page