You have to consult with an attorney familiar with administrative law as soon as possible. If you miss your deadline to request a hearing you can sometimes nonetheless get one if you can show that you missed the deadline for good cause. It sounds like you have good cause here, but you have to act on that as soon as possible. After requesting a hearing you and your attorney should work on building your case to show why the agency's proposed action should not occur. Sometimes that can be done by negotiation with the state, other times you just have to have a contested hearing. Either way it's best to be represented.
This post is offered as general information and is not intended as legal advice. This information does not in of itself create any attorney-client relationship.
You need to get the bottom of things, and find out a couple of things: Does DMV have your current address? How did they get notice of the positive drug test, and from whom? When did DMV send notice to you?
DMV can be very difficult to deal with, an experienced attorney can help you untangle what sounds like a web of confusion and clear your record.
This is NOT legal advice, please consult an attorney for an answer tailored to your situation.
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