Hi Terrance,

The Restore button on a historical OE Invoice will create a new Order based on the contents of that invoice. You don't want to do that.
AR and OE transactions are stored in separate files. As Steve said, they might possibly have been purged through current and history. Or perhaps there was a write error when posting the AR batch. Hard to say definitively.
You may not have security access to Recover batches in Receivables, if the highlighted batch has a status of Posted.

I agree with Doug that having your consultant take a closer look with you will likely get to the bottom of this faster than on a forum.