BBC: If you have relinquished your Nepali passport (thus citizenship, you are required a visa like any other non-Nepalese passport holder. If you live in the US, you can mail your passport or visit in person at one of the three consulates (NY, DC, Chicago). Alternatively, you can apply for visa at the KTM airport (immigration desk), but make sure you have exact change, or expect the officials to retain the change as a generous "tip" from the firangi. Good luck on your trip.