Is it possible to nurse a newborn that you have adopted? Is there anyway to start producing milk?

Yes there is and the process is called, "Induced Lacatation."

The "Ask Lenore" website has good information on this.
Ask Lenore ~ Breastfeeding ~ Induced Lactation ~ The Newman-Goldfarb protocols

Also check with your local LaLeche League, your hospital, your doctor for information. Some websites will suggest herbal remedies such as Fenugreek, Blessed Thistle, and Marshmallow Root. Some sites will say to take the drug Domperidone. But the best information is going to come from your doctor, based on your needs.

But adoptive Moms can lactate and breast feed their babies. Read what you can about it but always double check any information with your doctor.

Some sites include:
Induced Lactation -
kellymom.com :: Notes from Induced Lactation and Adoptive Nursing
Induced Lactation and Relactation