If you bought it from us, contact us, we can provide lost serial numbers and unlock EXEs, and we do so on a weekly basis for lots of people (who also fail to ever back-up their files

) - we will need proof of your purchase, which is usually just your full postal address and a rough estimate as to when you bought it. Even better would be a payment receipt, but if you didn't keep the program itself, I doubt you have that either
If you bought it direct from Tobias then there is nothing we can do, sorry.
Never trust a computer you can't throw out of a window