I receved a new job promotion after three years on my job.. I make 9.50 per hour for 40 hrs a week.. when I receved my promotion I was supposed to get a 50.cent raise.. my manger is acting like he doesn't want to pay us.. for two week now I haven't seen my 50 cent raise on my last two checked.. is there a law against this...

Do you have a contract proving that you actually got the promotion with your new salary? Without any evidence, it's difficult to enforce your case.