S.G.
I am not so sure I would clssify this as part of the terrible twos. All of us have nights when we wake up and can not go back to sleep. Kids are no different in that respect. They dont always know how to self sooteh themselves though and this is the part that can be fustrating.
If it becomes a habit the first thing you need to do is put up a baby gate so that she can not roam the house while you are sleeping. The set certain rules.
I remember my son waking up at this age one night. He woke me up and said he was hungry and wanted an egg. I got up with him and made him an egg and some toast with milk. He ate every bite, he really was hungry, the he drifted right off to sleep again. He was not being hard to handle he was just hungry.
Find out what will soothe her and then put her back to bed. Getting up with her and putting on a DVD may encourage her to get up again, it was a special time for her to be with you and watch the movie.
As hard as it may be to let her cry, you may very well have to let her. If all of her needs have been met, she needs to go right back to bed.