I live in Sri Lanka, and I use an HP Color Laserjet. I got stuck with outdated toner cartridges (genuine HP, but over 4 years old) which just died. So I went to the official HP agent
... and the manager tells me, "No, that warranty is invalid ... are you kidding, warranties on toner?" So I guess the "worldwide" warranty only works if you're willing to go back to the USA and file a complaint there. Anywhere else, good luck.