Tanya 

for backups have you check automatic backup locations?

article 12613  might able to help to see if you have backup.

Sage also provide data repair for some issues with Fiscal year end you can check article 22420 to call them

Do you have more details like what is latest transaction date? and Current Fiscal year start and end ? and what Year end suppose to be?  (all this is in setup, setting, company, information) These information can also help to determine what you can do.

Tanya Cederholm said:

I was prompted to change my year end date a few months ago, even though mine is not until Oct 31st, and inadvertently have been posting all my transactions in the wrong year

Tanya Cederholm said:

Is there any way to change this?

Not in a batch, but you can open the General Ledger (Transactions By Account) report (Under Show, un-check '[  ] Corrections'.

Double-click each transaction to 'drill down' into the input screen, click 'adjust', change the date, and click 'post'.  

If the program won't let you change the date, go to Setup | Settings | Company | System, and change the date for 'do not allow transactions dated before _____________'

This date can be set to stop yourself from accidentally entering transactions that would change a period that's completed / closed / reconciled.

I hope that helps, please post back!