Question: After copying the new site files to de main directory, I can not login into my WordPress backoffice, neither the one at the my developing folder. I have tried trough phpmyadmin also.
Answer: If you have tried several times with your current directory password and you haven't changed anything in the wp-config.php file, you need to reset your password from PHPMyAdmin. You should add this to your main site wp-config.php:
Somewhere next to other define lines.