I don't know what is going on, but for now, please use my firstname.lastname@example.org. This proves, in my opinion, that my email is alive somewhere, deep in the bowels of Yahoo!
I had filed numerous trouble reports with Yahoo and still have no explanation, but my missing email WAS restored and WAS all back. . . .
If somebody from Yahoo! is reading this, please act on it. Do you really want to give your competitor, GOOGLE and GMAIL that much of an advantage?
Merry Christmas and stay tuned!