fowl,
The firmware you have loaded to your player is not compatible. If you did not have a backup you need to now find another firmware that works for your player.
If your player is not recognised by Windows and you can no longer upgrade your player then the only way I know to fix it is outlined in the DEAD PLAYER RECOVERY GUIDE
HERE
Check on your mini CD as well sometimes a copy of the firmware for your player can be there. It will be a .bin file or a .fw file.