There is a solution possible from within Windows itself - I will assume this is similar to an issue I had with my GloHD some time ago as this does sound very similar.
First plug in your Kobo to the computer.
Open Windows Control Panel - Administrative Tools - Computer Management - Storage - Disk Management.
A list of your dives will appear. Check is there is a specific listing for the Kobo. If there is, check that a Drive Letter has been attached to the Kobo's listing. If there is NOT a drive letter attached, right click the listing for the Kobo, and click on Change Drive Letter and Paths. It MAY ask you to confirm that is what you want to do, click on OK, and allow the computer to add a derive letter for the Kobo.
You may or may not have to confirm your choice. on leaving the Computer Management screen, but regardless, your Kobo will now be accessible from within Windows Exploder (not an sp -
) and for whatever program you use to load books.
This is what worked for me and saved a "bricked" unit.