Reinstaller completement

killall mysqld
rm -rf /var/lib/mysql
apt-get remove --purge mysql-server mysql-client mysql-common
apt-get autoremove
apt-get autoclean
apt-get install mysql-server mysql-client

rendre accessible de l'extérieur

emacs /etc/mysql/mysql.conf.d/mysqld.cnf
bind-address            = 0.0.0.0
mysql -u root -pxxxxx
RENAME USER 'root'@'localhost' TO 'root'@'%';
FLUSH PRIVILEGES;

service mysql restart
my.ini
max_allowed_packet = 16M
sort_buffer_size = 256K

renseigner un nouveau mdp :

mysqladmin -u root password "new password"