You cannot restore it unless you have the exact version of quickbooks that created the backup, and you have absolutely no way of determining (from even the Properties) what version of quickbooks created the backup.

So you are out of luck.

And then even if you can figure out what version of quickbooks was used to create the backup, you will have to buy the older version and it probably is not available, even from Intuit.

Sound crazy? You are right.

It is unbelievable to me that Intuit has not addressed these compatibility issues. In my view the Quickbooks software product should bear a large warning on the label disclosing each version of Quickbooks is completely incompatible with all of the others.