What are the causes of soft palate collapsed? what does it means?

Makes no sense!: soft palate is a muscle like structure which is not prone to too many changes. I do not know of any term labeled 'collapse'. So you can ignore it unless you have some local symptoms on the roof of you mouth. Your tongue can check it out for you.

Soft Palate Collapse: That's a new one one me. Have never heard the term. Please see your General Dentist, General Physician, specialist Oral Surgeon, or specialist Ear/Nose/Throat practitioner for examination and evaluation.