Switch from PSW T1 to Tier 4 (student)

1. I was having a PSW visa and I applied for T1 entrepreneur visa. Unfortunately it got refused due to error in the adv.
material and then the appeal also got refused. Now I am in the grace period of 28days and can I able to apply for student visa?

2. I have a MBA and if I can able to switch to Student Visa: Can I able to do ACCA-UK

3. Can an educational establishment will offer me a CAS as my passport with the home office?
What do I tell or show them to convince them that I am genuine student to obtain the CAS?

If an educational establishment is willing to issue a CAS you can apply for a visa. Given your immigration history and current status and the general fear in the Tier 4 Sponsors you will struggle to get a CAS.
As for ACCA - as you have a masters that course will not meet the need. You have to step up beyond that level to PhD.
As for the passport - I doubt very much you will need it as there is virtually zero chance of getting a CAS at this time. But if you are going to try you will need a certified copy from the HO. Soon as you show that document it will ring alarm bells.