How to get a guy that i like?

i know everyone says to be yourself, but when i be myself it just doesnt seem to help? am i not likeable? im so confuzed on what to do! this guy i lik is nice to me, and he talks to me. only sumthimes. and he can be flirty sometimes. but lik when he talks to me i dont know what to say or do! i jus kinda mumble something and i get real shy arond him. im a prrty out going person, but whrn im with him i get all quite andshy. and when i talk my voice comes out rough and skeaky. i usta talk to him alot more and then wen i realized i liked him i became shy, and even he noticed it, he lik told me that i changed over the weekend, but this was awile ago. i just need help being my self again. i even tried to pretend i didnt like him so i would act noraml, but it didnt work, and i opnly talk to him in one cl, andd hes popular and im not.