ANSWER:

To restore, all you need to do is:

sudo mv /usr/bin/php-old /usr/bin/php

You just renamed your original php binary – next time, take care what you do with sudo privileges.

If you want to use MAMP’s php as default, consider adding the following to your ~/.bash_profile file:

export PATH=/Applications/MAMP/bin/php5/bin/:$PATH

by slhck from http://superuser.com/questions/424477