Nginx problems

Hello! I have a server with Ubuntu 18.04, installed nginx 1.15 + php 7.2 + mysql + phpmyadmin I have three problems with my server. The installations all happened ok, I'm just having small problems that I've tried several ways to solve, but I still haven't managed. The problems: 1 - In '/etc/nginx/sites-available', I change the root directory from /usr/share/nginx to /var/www/html I have set chown -R www-data in /var/www/*, but, dont works too. But, I get this error: unix:/var/run/php/[login to view URL] failed (13: Permission denied) Automatically, for this same reason, phpmyadmin does not work, even if symlink is created in /var/www/html 2 - I cant use root password in mysql -u root -p, this return: ERROR 1698 (28000): Access denied for user 'root'@'localhost' Automatically, I also can't login as root in phpmyadmin. 3 - Bind error 2020/05/22 01:10:29 [emerg] 1331#1331: bind() to 0.0.0.0:80 failed (98: Address already in use) 2020/05/22 01:10:29 [emerg] 1331#1331: bind() to [::]:80 failed (98: Address already in use) There are three errors that I am not able to solve, even searching a lot on google. The condition to fix my server, would be, entering my pc via anydesk / teamviewer and doing it in front of me. The terminal will be logged in with the root user.