Systems check the start date of the new financial year with the last date. Normally it doesn’t allow to create periods in back date. However, you can create future periods.
If transactions has not been posted, i will suggest you to delete all the periods and create the periods fresh as per requirement.
I have not posted any transactions, however system does not allow me to delete the period with follwing message “Fiscal year cannot be deleted because not all periods are open” I have not done any period closing but the period at the begining of the year are having the status as “closed” this has been created by default by the system. I am unable to change the status of the period.
As I understood your issue is on the 2009 invoices. I think you do not need to open 2010 period for this. this invoices will be included in the outstanding balances of your AR/AP awaiting settlement. I believe it is better to handle this by manually encoding the “due date” located at the invoice tab of the general journal. I assume that these invoices are part of your beginning balances.