Transfer to General Ledger (Assets)

HI,

Need you guys help before creating an S.R

Issue:-
User accidentally ran  Create Accounting process from Fixed Assets with Transfer to GL set as No in April and Dec 18 for a few run. We did not realise this until Post Dec-18 close. We spotted this in Jan-19. We Journalised the items and balanced our book. But we want to reverse the Manual Journals and transfer the un-transferred Journal entries to General Ledger before Year End which is the 31st of March 2019.
We attempted to change the period in GL and post. We executed the following steps
Open December-18 in GL ,