WIN10 -Unable to run MySql server after installation - 5.7
A few potential issues:


In your my.ini file, remove the trailing \ from the datadir variable, and change the remaining final \ to /. You path will look like ...\MySQL\MySQL Server 5.7/data
Whatever user you are running mysqld as may not have permissions on C:\Program Files\MySQL\MySQL Server 5.7\data. If you installed as administrator, try running command prompt as administrator. If there is a service registered for MySQL, open up services.msc and start it from there.