MySqlD does not start in newest OSX Yosimite version.

Start Terminal and sudo as root user

In you Applications folder find your installation. For magento bitnami you will find magento-version.. so you will have to look for it.

In …/mysql/scripts/ edit the file  ctl.sh

Right after #!/bin/sh  add on a new line:     unset DYLD_LIBRARY_PATH

And start all.