Megan Lane: 2 books

Cassiea never thought returning a necklace would get so complicated. Because of that one decision, she was transported to a world, hidden from Earth by the Elvains. They were magical beings who, for centuries, been waiting for her to appear. They told her that she was the reincarnation of an evil...

Cassiea was just getting a handle on her magic when the lord of the Elvain's asked for her help on an important matter. Unsure of her own abilities, she agreed to help in any way she could. He needed her to send him back to the past to prevent an evil sorcerer name Norus from finding the Sonjuna stone....