friends

i have had plenty of friends but resently some have changed they dont talk to me as much any more like one of my friends now never talk to me and they have what we call became a "cool" person because she always hangs out with the people we used to get anoyed by but she hangs out with them all the time and i feel like she doesnot care about me or any of her other friends i mean i have known her since 2nd grade and i was the first person to walk up to her(she moved from out of the country to here)and said hi and wehave always been good friends until recently
please help me what should i do?