www.makemkv.com

Help me please!
Acquired the program. The key is lost.
How to restore it

Step one: Check your email for a message from "avangate.com", which would contain your registration code.

If that fails, step two is to send a message to support@makemkv.com with your information, and Mike can look your key up.

Your wording of "Acquired the program" is strange, though - acquired from where? The way it reads implies that you picked up the program second hand, which is unusual, since licenses are issued to people, not to copies of the program.

Emails are lost.

Of course, the program was downloaded from the official site and acquired the registration key.

The registration key was saved on the computer, the computer is no more, respectively, and the key

Then you're "stuck" with contacting Mike at the support email.