Here is the query to find out the status of GL and PO Accounting Periods from back end:
SELECT sob.name "Set of Books" ,
fnd.product_code "Product Code" ,
ps.PERIOD_NAME "Period Name" ,
ps.START_DATE "Period Start Date" ,
ps.END_DATE "Period End Date" ,
DECODE(ps.closing_status, 'O','O - Open' ,
'N','N - Never Opened' ,
'F','F - Future Enterable' ,
'C','C - Closed' ,'Unknown') "Period Status"
FROM gl_period_statuses ps ,
GL_SETS_OF_BOOKS sob ,
FND_APPLICATION_VL fnd
WHERE ps.application_id IN (101,201) -- GL & PO
AND sob.SET_OF_BOOKS_ID = ps.SET_OF_BOOKS_ID
AND fnd.application_id = ps.application_id
AND ps.adjustment_period_flag = 'N'
AND (TRUNC(SYSDATE) -- Comment line if a a date other than SYSDATE is being tested.
--AND ('01-DEC-2014' -- Uncomment line if a date other than SYSDATE is being tested.
BETWEEN TRUNC(ps.start_date) AND TRUNC (ps.end_date))
ORDER BY ps.SET_OF_BOOKS_ID,
fnd.product_code,
ps.start_date;
Source: Metalink Doc ID 1317136.1