It's been ages and you haven't gifted anything to your girl. Reason? You have no idea what you should gift her.
Here's some quick and easy advice:

Think about what all she Likes
Pay attention to what she likes to do when the two of you are together. What movies she likes to see, what kind of clothes she likes to wear, what kind of foods she gorges on, what are her favourite colours, her intellectual inclinations, the music she likes to listen etc. This will give you an idea about her general tastes in life. If you think you are one of those who find it hard to judge people and ascertain their likes and dislikes, then go ahead and ask her. But don't make it sound too obvious to her that you want to buy a gift for her.

Think about the kind of Person she is
Is she a brand addict or all she cares is that she should look good in whatever she wears? Or is she one of those who hardly care? Or is she a tomboyish girl who enjoys climbing trees and running around bare feet? Is she obsessed with chocolates? Try and explore her inherent nature and thought process. Try to determine the things that give her true happiness. At the same time think about what she does in her spare time. Maybe she likes sketching, so you can get her a sketching set. Or maybe she likes gaming! So you can buy her a PSP.

Also, it'll be worth doing some brainstorming. Try to recall past conversations to see if she ever gave you any hints about presents or stuff she would like you to buy. Think, if she has been planning to acquire something for a long time, something which has been on her wishlist since ages.

Talking to Other People
Get the journalist in you to do some work. Talk to her friends. You can even talk to her mother. Usually a friend or a parent can have a really good sense of her tastes because of knowing her for a long time and would be more than happy to help.

Go Out and Get it
Once you've done enough research, it's time to go out and procure the gift. Do not spend months in just doing the research. At the most, take a week's time for that. You have to decide upon some thing or the other. Once decided, go out and buy the gift. Get it nicely wrapped. Attaching a personal note with it is strongly recommended and she is sure to love it.

Sometimes, the Simplest Things Work
It is not mandatory that you have to buy fancy jewellry for her or some other expensive stuff. Sometimes, even the most simple things can do wonders. Buy her a simple flower, and if you are close to where she lives, leave it on her step. Also leave a little note saying something like "I'm thinking of you" or other nice things. Even if the girl doesn't like flowers, she will like that fact that you're thinking of her and think it's kind of romantic.

No Cash at all
Whatever you do, please don't give her money. If you can't figure out what to gift her, then give her a shopping voucher for a good store but no money, for Good Lord's sake!

Experimentation is Welcome
If you think that usual stuff like clothes, CDs, etc. can be quite boring, then there's no harm in walking an extra mile and doing something different. You can get a t-shirt designed for her or get custom made handicrafts. You can gift her a vacation to the hills, a hand-painted portrait, etc. Such things are sure to excite her and make her fall in love with you all over again.

Nice sharing but I think you should come with some of your own ideas and writeups. I have already seen it on a site..

PS:
Here is the site where I saw it .. mensxp.com/dating/dating-tips/5463-how-to-buy-a-gift-for-your-girl.html

Buddy are u serious i end up finishing my pocket money on 15th . The next fifteen days are hell for me , for me no gifts to my girl . Se wants , can leave me anytime.

@Natasha : Could be possible ma'am. These things are common. Even websites do share stuffs like this.
Here. its just a sort of advice or rather options that one can consider when purchasing a gift for his partner. Well if you ask something about me, as what my idea about gifting something to a girl, it would be something really weird..... like sitting on a beach around a bonfire at night....with a guitar in hand.....and some lovely songs in her name. But this sounds really weird..... n is not possible practically...so I dont suggest anybody for such a thing. :-)

Anyways..thanks for your valuable comment.


@Ravinder : Hello Sir, how are you ?? I never said, its necessary to give a gift to your girlfriend. Also, I never stated, the gift should be expensive so much so that you run short of your money or disturb your budget. Its just an advice sir to help you out. I dont think so, your girl ever demanded a gift from you. Its just love that you have gifted her something.

I would appreciate if you can share here what you gifted her, if ofcouse, it doesnt hamper your privacy.
Thanks for the comment. :-)

I think it whould be a better idea for gift your girl you should ask her what she want many times these kind of poblems happend in life