Hello,
That sounds pretty strange. The first thing I would do is try to run MySQL from the command line, because if it dies it will be obvious, because you will be back in the terminal.
run /usr/local/mysql/bin/mysql . At least, that it where it should be. Editing the PHP should have nothing to do with the database, and MySQL should be pretty robust. Try to find an error message somewhere, because then online fourms + docs should get you on your way.
Good luck