Welcome to NeuroTalk.

Your post sounds quite alarming to me. One cannot live long with a B12 reading of zero.

You can take daily B12 orally, for pennies a day.

Here is an informational thread I made a while ago combining the newest information for people visiting here:
http://neurotalk.psychcentral.com/thread85103.html

Typically when people are so low in B12 after testing, it may be given daily for 7 days by injection, then weekly for a few months, until the levels become normal. Then injections once or twice a month. Today we know that oral use of methylcobalamin can cost pennies a day, and is very effective, so injections are not really needed past the acute phase. I'd call your post very acute!

You should be tested to see if you are gluten intolerant, which may impair B12 absorption from food. Hereditary problems are called pernicious anemia, and require B12 treatment for life.

When B12 is very low for a long time, you may become permanently disabled. Some damage to the spinal cord or brain may not heal if beyond repair.