Is my original Mojang Minecraft purchase no longer recognized?

My problem is that I bought a pass to play Minecraft a year or two after it was released,when it was only $10. I'd like to play again on my WinXP addled computer. I can't run x64 bit software and that is what the latest Java requires. I can't run that either.

Point is, is my original Mojang purchase no longer recognized? My account login sure isn't. Just wondering if I wasted my $10 on a game that I've wanted to be able to play again for a long time.