It would appear that your fermentation is "stuck" (the yeast has gone dormant). How did you aerate the wort before pitching the yeast, and what temperature was the wort when you pitched? Is this an extract recipe?
To fix the problem, you could try increasing the temperatures into the low 70's for a few days and see what happens. You may have to prepare a new batch of yeast and re-pitch fresh yeast if the activity does not pick up.
"Give a man a beer, and he will waste an hour. Teach a man to brew, and he will waste a lifetime!" Bill Owen