If you wish to see the list of previously opened company files that would be displayed inside QuickBooks when QuickBooks is open, but no company file is open, without opening QuickBooks, you can query the registry key
HKEY_CURRENT_USER\Software\Intuit\QuickBooksCommon\QBFinder
using the reg query
command. E.g.:
C:\Users\JDoe>reg query HKEY_CURRENT_USER\Software\Intuit\QuickBooksCommon\QBFinder HKEY_CURRENT_USER\Software\Intuit\QuickBooksCommon\QBFinder 0 REG_SZ c:\users\jdoe\documents\quickbooks\csi\c.s.i.qbw|23|professional 1 REG_SZ c:\users\jdoe\documents\quickbooks\moonpoint\moonpoint.qbw|23|professional
The .qbw files displayed would be ones you could select by clicking on them from the "No Company Open" window inside QuickBooks. The "|23|professional" at the end can be ignored, if you only want to know the file names and locations. The directory path and file names displayed can then be used to backup any relevant QuickBooks files to another location for archiving, for instance, without needing to open QuickBooks.