A week or so ago I was looking for a sample of using the Media Foundation AAC encoder and I found this repository by K F Yang:
When I attempted to revisit it this week it appears to have gone:
The user amamiya's activity also doesn't show this project:
Is there any way to find out why it disappeared, recover any of its files or a way to contact owner?
It disappeared because the owner deleted the repository. You may find contact information on the profile of the owner, but in your case the owner decided not to publish any contact information for as far as I can see (except some initials + last name in the README). So I think you're out of luck. You might be able to find an older distribution somewhere though.