[php] I can't access http://localhost/phpmyadmin/

I had the same problem. Couldn't access http://localhost/joomla neither.
and I did not quite understand the other answers.
The simple solution for me:

  1. stop all actions in xampp (I had apache and mysql running. apache on port 80 and 7000something)
  2. quit firefox
  3. restart the actions (apache and mysql)
  4. restart firefox.
  5. open http://localhost/phpmyadmin (or http://localhost/joomla - whatever it be)
  6. voila!

Now apache runs on port 80 and 443 and mysql on 3306.