What do you do if your best friend suddenly gets amnesia?

My best friend, Sarah, got hurt in a cheerleading accident when she didn't fully land her back tuck. I tried talking to her, getting her to remember her nickname, getting her to remember who I am. She remembers nothing. She says that when she woke up, she was told her name was Sarah Newton, her best friends are Ally Watson and Micayla Harvey. How can I help her remember? Any ideas?