Does anyone know of a work out that really works?

Im looking for a sure fire work out that will work I've tried everything from diet to gym to work out dvds even buying the gazelle and the ab lounge and none of them seem to be working,I had my 4th child 7months ago and I have done everything but starve myself and I cant seem to lose a pound,after giving birth to my other children I was able to bounce back after while with diet and exercise but its not working for me this time,Im not used to being a certain size the only thing that has gotten smaller on me is my face,can someone recommend something I really need it