I've never used DeskCNC, but is there a way to set a zero point manually? It sounds like you've lost the offset values between the "home" position and the start position you set your stock to, which corresponds to the origin point of your drawing. I can't tell you how to restore them, but in the meantime you should be able to reset the DROs to a "floating zero" that can be anywhere you want. Many machines don't have home switches at all, and work just fine - they just need to be told where to start.