I have a problem in remembering what i have studied i forget it after few days.?

Well there is always the chance that you have attention deficit disorder. From what you've said it sounds quite possible. I suggest seeing a psychologist/psychiatrist for help with it. There are places on the internet you can go (just type it into google) that have techniques for helping memory. There is also the possibility that you really didn't care about those certain events, so your brain discarded them as insignificant.