Hi, so if you put the latest release on to the old laptop it will work, it was just the firmware that needed to be updated.
If you have the 6-digit SN that the MyDMX 3 interface shows when its plugged into Hardware manager, that is all we need to find the original account and email address. See the image attached for my example, but i marked over my SN of my personal box.
But feel free to email me the SN of your interface and i will send it to the web store guys and they can assist you from there. but i am sure once you are logged back in and synchronize, all will work.