Cant access mysql root on new Centos server

I just created a new Centos VPS and then followed the LAMP setup tutorial.

I now want to install Wordpress via SSH (I dont want to do the one click installation process)and I need to login to Mysql to create a new db but when I run this:

mysql -u root -p

and then hit enter to enter a blank password I get this:

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: NO)

so then I try it again but I enter my root password and it returns this:

ERROR 1045 (28000): Access denied for user 'root'@'localhost' (using password: YES)

also tried running this:

service mysqld start

which returns

Failed to start mysqld.service: Unit not found.

what do I need to do here?

edit: this is with MariaDB btw

and some more info:

sudo systemctl status mariadb.service

says its enabled and running:

 Loaded: loaded (/usr/lib/systemd/system/mariadb.service; enabled; vendor preset: disabled)
   Active: active (running) since Wed 2017-03-29 13:52:43 +07; 2 days ago

and then

sudo rpm -q mariadb-server

shows this:

mariadb-server-5.5.52-1.el7.x86_64

and this:

yum list installed | grep mariadb

returns this:

mariadb-server.x86_64 1:5.5.52-1.el7 @base

and finally when I try running this:

/usr/bin/mysql_secure_installation

I get this

touch: cannot touch ‘.my.cnf.23570’: Permission denied
touch: cannot touch ‘.mysql.23570’: Permission denied
chmod: cannot access ‘.my.cnf.23570’: Permission denied
chmod: cannot access ‘.mysql.23570’: Permission denied

NOTE: RUNNING ALL PARTS OF THIS SCRIPT IS RECOMMENDED FOR ALL MariaDB
      SERVERS IN PRODUCTION USE!  PLEASE READ EACH STEP CAREFULLY!

In order to log into MariaDB to secure it, we'll need the current
password for the root user.  If you've just installed MariaDB, and
you haven't set the root password yet, the password will be blank,
so you should just press enter here.

Enter current password for root (enter for none): 
/usr/bin/mysql_secure_installation: line 232: .my.cnf.23570: Permission denied
/usr/bin/mysql_secure_installation: line 233: .my.cnf.23570: Permission denied
/usr/bin/mysql_secure_installation: line 234: .my.cnf.23570: Permission denied
/usr/bin/mysql_secure_installation: line 236: .my.cnf.23570: Permission denied
/usr/bin/mysql_secure_installation: line 205: .mysql.23570: Permission denied
/usr/bin/mysql_secure_installation: line 207: .mysql.23570: Permission denied