What happened to the group of colonists
We don't know what happened to that group of colonists that disappeared. They never knew what happened to them, but maybe they died because of low food supplies, Then again, they could of died because of bad drinking water.
A different group
In 1584 another group led by Phillip Amadas and Arthur Barlowe found Roanoke Island before the English. They also left the island for unknown reasons.
How they survived
They didn't stay there for long because of low food supplies. While they were there, they had boats, guns, and tools. Their resources were wood, which they made houses, forts, and boats, and plants for food and medicine.
Queen Elizabeth gave a charter to the second group so they could claim the land for her. Plus, you know land equals power.