i am in love with a sister of my classmate. she is a very nice girl and i like to ask her out but her sister hate me and never let me get close to her wat should i do?

before you speak of this to the girl of which you are attracted... you need to speak with her great-great great-great Grand Mother and her neighbors in the old country. If they give you permission to speak with the girl of which you are attacted, then you must pass three test before you can go any further with this idea. The test will be known while you sleep and dream. You will need to meditate on the image of clouds and ponder their purpose on our planet. Do they exist only to drift and disapate? Do they exist to carry motion into the lives of every living being stationed on this planet. Do they exist to be alien to our credit cards and our touch-screen phones? Or can the clouds tell you how to be Human, and what to do when you are attracted to a Human being? The cloud has no buisness telling you - who you can or can not speak with about the logic and/or emotions of LOVE. ~ Love is a Cloud, and Love is Free.

why be depressed dumbass.. its no biggie really.
what you need to do is get in good terms with your classmate first then it will be much easier to get to her older sister. she's like the gatekeeper. just don't let your classmate fall in love with you or else she will shut the gate at you and won't be able to cross to her elder sister coz she'll want you for herself. got that? now be nice as a friend but not too nice to let her fall for you. she might even help you out with her sis if you become best buddies with her. that would even increase your chances by several folds.