What would you do if you liked someone badly but don't know how to talk to them?

Same thing happened to me. If the person you like has Facebook, start talking to them there. Then next time you see the person, you will have something to talk about. If you start talking first, then you have done your part and should wait for the other person to start a conversation. However, if you are getting impatient, go and start the conversation. Just imagine it like you are talking to your best friend. And who knows, something may work if you start talking. All you have to do is say Hi.