I and my younger sister at present moment don't talk with each other.it has been almost 2years.I suspect the reason was when my dad kept both of us at the same hostel.at hostel time we didn't used to talk with each other.due to this reason we don't talk to each other very often.we talk very rarely.On top of that she's now at teen age and I think she's roaming a lot with her friends.
WILL I BE ABLE TO TALK WITH HER AGAIN NORMALLY??

Sure you will, just say hi, how are things going, and then let her do what she does with her friends. Don't try to force it, as just saying hi every now and then when you think of her, is a great thing.

Since she's only a teenager, then you need to be the one to take the initiative to talk to her.

Just talk to her like nothing ever happened and you may be surprised to see that she may warm up to you.

Aaah! These things looks so diffficult for me.from where should I start??

How about telling her how proud you are that she is your sister, and that you love her. Tell her what you are telling us , that you want to talk with her, to actually get to know her as a person. That you just want a chance.

It is never to late, regardless of age. Although since she is a teenager, she might be more susceptible to open up opposed to an older person. That is not factual, by the way, pure opinion based on prior experiences.

So I would definitely open yourself up to her. Strike up a coversation. Become very interested in her life. Don't be condescending either. Just talk and soon she will open herself up to you.