Sorry - have been away a few days.
If you can't send your Audya back and you have missing system files you can request a system restore disk through your distributor. (presumably you did not back up the hard drive data yourseld?)
Not sure if there is a version 4 restore set yet, but it doesn't matter as the USB pendrive contains everything you need - so even a version 2 set will be fine (but I know Ketron produced a version 3 set)
If you are worried you have messed up the data on the pen drive, they are not expensive so order another at the same time.