Theres this guy i like.......and i dont know what to do can someone help?

Ok i really like this guy named alex and i have liked him for a while hes my ex boyfriend but anyway every time i talk to him in person its like he cant talk back hes stuck its like hes scared of me im only 12 and hes 14.......when we dated before it was like a txt realationship and now idk what to do.....he's vey quiet