I have a problem with my XAMPP server. I can start Apache, FileZilla, and every thing else without problems, but when I try to start MySQL, it just says
Though this is late, I'm sure it would help someone in future.
First run which mysql.server to know where mysql is located on your machine. After then run sudo /usr/local/bin/mysql.server stopto be sure that no other mysql process is running. If no other process is running, you would definitely get an error saying MySQL server PID file could not be found!. That's fine.
After then run sudo /Applications/XAMPP/xamppfiles/bin/mysql.server start to start Xampp's mysql server. When you go to the Xampp GUI, you should see that mysql status as running.
Please note that this is for OS X users.