Nancy McLaughlin GREENSBORO — Another birthday has passed with Tyarra Williams still missing.Investigator Mike Matthews sat with thick Greensboro police case files bearing the aspiring teacher’s name on the day she would have turned 28.Williams’ case has captured a large social media following partly because of the eight-year-old unsolved mystery of what happened to the Dudley High School graduate.Her story has been featured on Investigation Discovery’s “The Vanishing Hour,” the “Black Girl Gone” crime podcast and a special NBC News report on the missing. And others.But the media attention hasn’t resulted in much. Then or now. ****Williams was 19 years old at the time — she had just enrolled in college — when she stepped outside her Stoneybrook Apartments home off Webster Road about 8:30 p.m. on a frigid January night in 2016. She was to meet a friend in the same complex. The 5-foot-5, 120-pound Williams was dressed in blue Levis, a black jacket, a pink shirt and a royal blue toboggan....