If your diploma is not from an accredited school, the USCIS may or may not accept it as satisfying the high school requirement.
If you want to be sure that you meet the requirement, you could take the GED or other equivalent state-authorized exam. Good luck!
These answers are provided for educational purposes only, and should not be construed to be either formal legal advice or the formation of a lawyer/client relationship. For specific legal advice that applies to your individual situation, you must be a client of this law firm.