I used to sleep over 9 hours a day?even I sleep enough I feel most of time sleepy specially when I studying I can't concentrate because of feeling sleepy?tell me what are the results of over sleeping and how do I cure from this bad things?

I've overslept a few times and I feel so crap the next day!
Anyway I've found an article that might help you.
Oversleeping - Causes and Effects
And this is the main page
Sleep Less and Live More by Becoming an 'Energetic Early Riser'

:)