Change of status from H1b to F1 Denied so that he is technically out of status. He has master degree in computer science. Is there any immigration expert who can provide any information regarding this situation?

I am not sure if you are serious about the help you are seeking. Else, you would elaborate on the circumstances of filing and reasons given for denial.

Shouldn't have applied for F1 after H1. The latter is dual intent and once you apply for it you lose the privilege to file F1 or other similar single intent visa.

Best option might be to look for another company to apply H-1B. But if you have to start a new process on H-1B then you have to wait till October to get a job as the quota is over, unless you get a job in an university.

He is waiting for the letter from USCIS. I don't know the reason why they denied change of status even though he applied immediately after he laid off.

He... she..?? who???

Kakadaka,
Please read the reply by stiffler. Your F1 will be denaied if you have residency intention. But again, H1B is dual intention visa and you do not have residency intention until you apply for GC or labor certification.

So, F1 status should not be denied if you haven't started GC processing. Just being on H1B doesn't qualify as residency intention. You should consult a lawyer.