if period is finally closed can it be possible to open it, because due to this year end processing can not be done.

I think GTM would be your only choice in this case.

We had to have Baan Support perform GTM to re-open finally closed periods for us.

Indeed, the GTM is the only way to reopen the period. Be aware that this should only be done in the current year, in case you accidentally finally closed a period.

If you do so for already closed fiscal years and you make some changes, the closing balances will alter and thus no longer be the same as the opening balance of the next year... unless you change that as well. Baan does not support that in any way.