I am sorry to discover this thread so late. I have a son with Autism and I know that challenges that you are facing. I can advice only from my experience.

First of all, do not think she is "sick". It is not a sickness that can be cured. She most probably have some sort of high level autism that was not diagnosed and treated properly during her early childhood. As such, she got abused in school and home because people think she is just being "difficult". That trauma has manifested into serious mental disorder which she developed to cope with by staying in bed doing nothing. That is her "safezone" where no one can cause harm to her. I feel really sad as I can imagine the kind of things she has gone through for the past 21 years. I do not want to question on why she her issue was discovered so late but that is one mistake that really caused something very very hard to recover from as she is already an adult and it is very hard to teach her to live with her condition. Still, there are still a lot of things that can be done and if proper intervention can be applied she can live a better life and even be independent.

Secondly, please get her diagnosed properly what kind of "learning disorder" that she has. Send her to proper psychiatrist and NOT hospital. You can contact NASOM (google for this) and see if they can help to diagnose her condition. It is really important to find out her exact mental disorder as it could be more than one condition.

Thirdly, please know that there are no "cure" for this kind of problem. Medication cannot really cure the problem. It only suppress her mental state and sometimes it causes side effects that make things worst. The only way to deal with this is to be patient and teach her to be independent. A lot of high level autistic child are actually very smart and can do things that sometimes no normal people can do. Some became math wizard or famous artist and so on.

The most important thing is for your family to accept that she is special. Do not blame her for things that she does as she does not have the capability to act like normal people. Be kind to her and patience. Use positive enforcement to encourage her to do things. Like example, if she like chocolates, tell her you will give her chocolate if she go to toilet properly.

I have been trying to create support group for parents with autistic child for many times in this forum but Malaysians parents are just too ignorant to admit their child have this issue. This is the exact thing I was trying to teach parents and avoid late intervention. Damn it!

Every autistic child is different. Rewarding and punishment system can be adjusted accordingly. Methods that work for a child might not work for another. The family would know better and need to adjust accordingly. Also, the system will not work forever. It need to be changed to adapt to the child's age. Trust me when I said I have tried all the methods there is on my child. Sometimes it will work for a few months then it will not work anymore. However, for some, it will work well and long. As for the chocolate thing, since I do not know the whole story I will just say that do it with some thought. Don't just give him chocolates until the child become obese. Key to living like a normal human still applies. I know it is not easy and straightforward but keep on persevering. Don't give up. Whatever it is, do not ever deny that you child is special.

There are no cure to autism. Some of the child actually grew out of this when they become more mature and understand their issue. This apply to those who is not serious case. Remember there is no cure. There are claims by this person or that person eating this or that can "cure" it. You can try but do a lot of research and be skeptics about them. I don't deny maybe some medicine worked for some due to mixture of environment, condition of the child and so on.

Stay strong!