Thanks for the idea...
I really have no idea how it was removed... I tried to open it a day or so after it was last saved and it simply wasn't there, or anywhere else (temp folders, recycle bin, etc) , the backup file that OpenOffice made was corrupted, and there were no other documents anywhere on the hard drive that matched it for size or date modified, regardless of name. A mystery. Other unerase type programs have found it in My Documents, where it used to be, but haven't been able to recover it. I'm hoping Recuva might be the one that can.
I'm still unsure of how to search even the Recycle Bin, though - again, it only searches the I386 and Windows folders, not any other part of the drive. I'd be happy to search the entire C drive, if it would let me.