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.