If you can't login the WordPress control panel with correct password, prompt for password error, please try the following step.
Use text editor to open the files in wordpress install directory /wp-includes/pluggable.php
, change:
setcookie($auth_cookie_name, $auth_cookie, $expire, ADMIN_COOKIE_PATH, COOKIE_DOMAIN, $secure, true);
to
setcookie($auth_cookie_name, $auth_cookie, $expire, SITECOOKIEPATH, COOKIE_DOMAIN, $secure, true);
Save and close the file and login again. Please change before the backup file.