The only meditation that works for me is that of a Buddhist monk, Thich Nhat Hanh, or Thay, as he was known endearingly. He taught me to breathe and this is the only natural way I know to calm down. He has changed my life in my short time with him. I found him on the day he died. And now I breathe with him every day, sometimes more.
Here is his story if you are interested.
Take 15 minutes and listen and let him guide you in taking a breath and calming down. You WILL find peace.