US permanent resident returning home to the US after two years on a student visa

I am a permanent resident of the US and have a student visa in Canada. Now that I have completed a degree here, I will be returning home to the United States.

For financial reasons, I was unable to go back home to the States, and instead took summer courses in order to complete my degree requirements. It is now a little bit over two years since my last visit. Both my family and I are worried that without a travel document - a document that Department of Homeland Security issues to all green card-holders - the border official will consider my "US permanent residence abandoned" and deport me to the country of origin that I left nearly 15 years ago. Unfortunately, it is not the document I can apply for outside of the US. Nor can my family (both US citizens living in the US) apply for it on my behalf.

To take things one step further further ... more than a year ago (May 2008) I applied to renew my passport from the country of citizenship in the Canadian consulate and to this day have not received it. My intention was to get the passport here but now that it is taking such a long time and my student visa is soon to expire, I am in a limbo. By now, my old passport has expired and I cannot seek a temporary visa or restoration of my status here in Canada without a valid passport either ....

What are my options? Can I go to the US border without the passport from the country of citizenship and use my permanent residence card or should I wait for the passport to be renewed? What penalties may I face and what measures should I take to avoid them?

Many thanks for your response.