I hope I am not doing homework for you, but here is what I found:
“Interestingly, when Drake picked up these colonists, he left behind 15 of his own men, who were never heard from again. This foreshadowed one of the great mysteries of North America, Roanoke’s so-called “Lost Colony” of 90 men, 17 women and 9 children, founded in 1587 and discovered to be missing in 1590, but for the word “Croatan” carved on a post. Although both the English and the Spanish searched for clues to the colony’s disappearance for many years, the mystery has never been solved.”
Using the “teach a man to fish” principle, this is what I googled: number of missing Roanoke colonists. The link I gave you was the second listing to come up.