how to see prefrontal cortex is functioning well by a test? Is there a test to see if the Prefrontal cortex of someone works normally? especially a simple test like a questionnaire that you give the individuals to fill out and based on their answer you obtain results.

My next question, if someone's prefrontal cortex does not work normally, how that can be cured? I am looking for natural ways, natural medicines, or methods.
I'll tackle the first part of the question as cognitive training is a whole can of worms on its own: 

The function of the prefrontal cortex should be assessed by a trained neuropsychologist, who can administer the appropriate tests and compare results to reference data from the broader population. 

One commonly used test associated with prefrontal cortex function is the Wisconsin Card Sorting Task (WCST) [1]. For this test, the participant has to match cards according to changing rules. This test has been used extensively with patients with various neurological deficits and psychiatric disorders and seems to be sensitive to pathology of the prefrontal cortex. 

Questionnaire measures are generally quite crude and are usually only used as a screening instrument for more detailed tests. 

Reference:

[1] http://www.cognitiveatlas.org/task/Wisconsin_card_sorting_test