I got this error while I was messing around with MySQL root password using command line. Apparently somehow I had managed to damage the mysqld.exe file (MySQL Daemon).
I have read that there might be several reasons for this error. I did some googling and nobody was mentioning my reason of getting this error so I though sharing my case and my solution could help others.
As I said, in my case the problem was with the MySQL Daemon. If you have used the default installation, you could find the daemon under “C:Program FilesMySQLMySQL Server 5.6bin”.
Note: This is for version 5.6. Might change depending on your version of installation.
Check the size of mysqld.exe file. If that is 0 bytes then you have blown the deamon as I did.
To fix this you can just copy a good mysqld.exe file from another MySQL installation's “C:Program FilesMySQLMySQL Server 5.6bin” directory. Make sure that the installation versions are the same.
Then the error message should be gone. Your MySQL should work now.
If this is not the case for you keep googling.