How may people are affected by a personality disorder worldwide??What can we do to change?

[mistreata]

How many new cases of severe personality disorders will you have in a year?
How are the patients treated,medication is used in all cases, or is there an alternative way of treatment?
Do things improve in the menal hospitals or is it better ,for some patients ,to do their treatment at home?
Do patients know, sometimes, that they need treatment ,or they do not realise that they are sick?

[Jaquta]

You would need to look up a country's individual statistics for some of that info.  
Some personality disorders are under-diagnosed while others are over-diagnosed.

I tried to work out the number of people with bpd in my country and also the number of patients with this disorder each doctor must see.
From memory the prevalence rate of this disorder is 1-2%.  The population of our country is approximately 4 million and the number of registered doctors in our country is (was)10, 000.  I figured each doctor should see about 8 patients with bpd.  Although this would vary between specialties (with pediatrics seeing none and psychiatrists seeing the majority).  Anyway, there are five doctors working in the medical centre I attend but I am the only one diagnosed with bpd that they see.
The numbers may have changed since I worked this out ages ago.
The number of people severely affected was about 500.

I can answer some of your other questions based on personal experience.
My experience is that people with personality disorders get treated very poorly.  Psychotherapy is used a lot but nowhere near the intensity it should be delivered.  Doctors do over-medicate these patients.  Often there are other co-morbid conditions and these too predominantly get addressed through medication.  ECT is often given to some patients who clinicians find 'difficult' and who they don't understand.
Treatment should however be tailored to meet each individuals needs.  That may include medication, hospital, specific programs, etc.

My experience is that psych wards traumatize patients more and end up doing more damage.  Hospital can help stabilize and facilitate change but it needs to be used appropriately and not abused (by either patient or clinician).
I think for the most part, depending on the degree of pathology, that treatment is best done in the community setting.  For me, treatment is not better at home or hospital.  For me, symptoms mean I struggle with some issues which makes it difficult for me to move away from my family.  The invalidating families we are sometimes raised in means progress can also be minimal in a home environment.  Independent living would be a far better option than either 'home' or hospital.
For some people hospital can become a safety net and it doesn't provide space to learn new skills or learn take responsibility for yourself.

Some people are aware they have issues (and need help).  Some lack insight and don't see the difficulties they have or cause others.
For me, I have probably always felt different like I have never belonged and that maybe even that something was missing.  I had problems with anxiety, relating and body image growing up.  I only ever sought treatment for physical issues, although I did at one point say I had felt suicidal, and my GP referred me to a psychiatrist from there.  After my initial diagnosis of severe depression it took another five before I was diagnosed with a personality disorder.
I think we see things from a different perspective and don't realize the affect our personality organization has on us or our life.

What can we do to change?  It depends from which perspective you ask that (from a health professional's, a patient's, etc).  If from a patient's then possibly engaging in long-term psychotherapy.

[Roger Gould, M.D.]

Those are a lot of very general questions...and the answers are yes and no, depending on......people improve in a variety of setting with a variety of treatments, medications usually not necessary but sometimes helpful.