Never told about or offered disability benefits

[Guest]

Hi, I'm looking for answers for a question posed to me today, I have a daughter who is now 19, she has been registered with many mental health agencies from about 6 years old, at the time I didn't realise I could claim disability benefit for her because of her mental health I was also never told about it or offered it, would it be possible to now have them compensate me for what I should have got even though she is now older? I was thinking along the lines of negligence, I was a single father with sole custody no other outside help and that benefit at the time would have made her life so much better.