|If the MySQL service has started, stop it. Open a "DOS" cmd window, and in it run ...|
<MYSQL_HOME>\mysqld --defaults-file="<MYSQL_HOME>\my.ini" --console --skip-grant-tables
is the full path to the MySQL installation folder. With MySQL 8 add
--shared-memory to the above cmd, for reasons why see https://bugs.mysql.com/bug.php?id=90554.
If the cmd generates an error, deal with the error then try again. Once it succeeds, mysqld hangs, which indicates the server is running.
Now open a second cmd window, and in it run
There execute ...
select host, user, password from mysql.user;
Edit the entries to suit, delete any rows with a blank user value, then issue ...
Exit mysql, then run ...
Switch to the cmd window where you started the server, and run ...
<MYSQL_HOME>\mysqld --defaults-file="<MYSQL_HOME>\my.ini" --console
Now in the 2nd cmd window run ...
<MYSQL_HOME>\bin\mysql -uUSR -pPWD
PWD are user & password values you just created or edited. If one of those values is still wrong, repeat the whole sequence from the top.