lost the return envelope for iPod nano (1st generation) Replacement Program

I entered my details and was sent a prepaid envelope to return my 1st gen ipod. Then I went abroad before I could send the iPod and I'm still away. Sadly, I relied on someone to do it and gave them the envelope and but they threw away the envelope for no apparent reason

How can I get a replacement envelope? I'd prefer if I can just send the iPod to Apple at my own expense. if possible, what address should I send it to and what information should I attach with it?

Thanks