If i used to like boys, but now only girls what am i?

Sexual attraction, much like gender, can be fluid, so your sexuality might have shifted to where you like girls instead of boys, and there's nothing wrong with that.

If you're a woman, it may be that you thought you liked boys because that's what society expected from you, and you were influenced by that. And then, later you found out your true attraction. But if you believe your attraction to boys was deep and true, then maybe you are bisexual. Being bi does not mean you always like boys and girls at the same degree, some bisexuals are more oriented towards one gender, and for some, the level of attraction towards the different genders changes throughout life. However, you are the only person who can know for sure! And remember, orientations are nothing more than what we feel we are. If you feel like one label reflects who you are more than others, and you wish to identify with it, that is your orientation. Not labelling yourself at all is also a possibility, if you're not confortable with any definition!