I'm a mom also, and I'm sure you feel like you've been thrown a curve ball with your daughter failing a screening test. I'm sure you are a mom who cares and wants the best for your daughter. It's okay. Take a deep breath.
All you know right now is that she failed a screening. You really won't know anymore until she has the comprehensive testing and you can talk to professionals about what exactly is going on. When you have more information, which can be difficult to sift through, you will be in a better position to ask informed questions.
The person that gave your daughter the hearing test should had told you what happen next. How is your daughter doing in school , is she failing behind in her grades? You should talk to her teachers and find out and bring your daughter to audi to see what kind of hearing aid would be best for her hearing lost.
I agree with Seb. You need to go to the ENT (Ear, Nose and Throat) specialist and have him or her examine your daughter's ears. It is like a detective trying to find how she lose her hearing at 13 years old. He or she will give you the results.
I am surprise that the person who gave the screening test for hearing did not give you the results of why she failed her hearing test. Maybe she or he did not know anything about hearing loss. So best bet is ENT.
After that, you might get advice from the ENT specialist to go to the audiologist for hearing test (sound exam) and new hearing aid(s). I don't know. They will work it out for you.
Please try not to listen to the medical professionals that she is not suppose to sign ASL. She has a right to decide which language method she could choose. Never force her to do what you want her to be like a hearing person. She has to accept her deafness into her journey. She will be fine.