I would not close HER door but I would definitely close YOUR door. Closing a child into a room at this age can be scary and may terrify her. I would put a gate to the entry of her room and just let her figure it out. Close your door so you can't hear her, assuming nothing is in her room that can harm her (tipping over book shelves, exposed outlets, etc) and then let her cry it out. I would completely not suggest to just keep getting out of bed and putting her back into her own bed and that she will eventually just "get" it. It won't happen. You will be awoken every single day for God knows how long. She needs to figure this out on her own and eventually she will wear you out and you will give in to her sleeping in your bed just for the sake of being able to sleep again. I promise you, putting a gate on the door will work. She will get upset but after realizing she's getting no response, no attention from you, she will return to her bed all on her own.