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Congratulations for having the desire and determination to further your education; you deserve credit for that itself!
You might consider calling your local school board and posing your question to them directly. They may be able to suggest a course of action for you.
Otherwise, please consider taking the GED exam. That will give you the equivalent of a highschool diploma.
Best wishes.
Dartagnian
Take a GED test, which is equivalent to a HS diploma.