Use the below Steps to reset the password.
$ sudo systemctl start mysqld
Reset the MySql server root password.
$sudo grep 'temporary password' /var/log/mysqld.log
Output Something like-:
10.744785Z 1 [Note] A temporary password is generated for root@localhost: o!5y,oJGALQa
Use the above password during reset mysql_secure_installation process.
<pre>
$ sudo mysql_secure_installation
</pre>
Securing the MySQL server deployment.
Enter password for user root:
You have successfully reset the root password of MySql Server. Use the below command to check the mysql server connecting or not.
$ mysql -u root -p
http://gotechnies.com/install-latest-mysql-5-7-rhelcentos-7/