As you said she was responding for sounds before,now she is not. Did she had any history of high fever, measles. ......
H/of cold or infection. ...
Try to rule out that first.
If she is having sensorineural hearing loss
Then she requires hearing aid, after fitting, she requires speech therapy
Next Steps
try to rule out infection. ..
Health Tips
consult audiologist
get impedance audiometry done to rule out infection