I rate this essay a 2. You appropriately addressed the prompt, but you also left a lot to be desired. You mention how you accomplished these three things but never explicitly state how you accomplished them.
For starters, I wouldn't advise starting your essay with I have accomplished many things in my life. - the prompt is asking for you accomplishments and this sentences does not add anything to the essay.
You could start out with: The year 2000 was one of the hardest years of my life, not only was I diagnosed with Schizo-affective disorder, but I also had to learn how to cope and live with my disability. For five years I battled with Schizo-affective disorder, however, in 2005, I reclaimed control of my life and got my life back on track. Now, years later, I realize that two of my greatest accomplishments stemmed from living with my disability, which helped catapult me to do more with my life.
In December 2010, after months of online courses and exams, I became certified as a computer technician. I have always been interested in computer and technology since my father introduced me to them as a child. As I grew older, my father taught me about the basics of computers, and as I grew older, my knowledge and passion for computer technology continued to grow. (talk more about how you became a computer technician)
Talk about why you chose to study for your G.E.D and maybe what you plan to do after you finish the program.
Do not repeat the sentence you said before as your last sentence. I understand that you were aiming for a powerful ending with the repetition to tie the entire essay together but in this case it does not come off effectively.
Just add more to the studying for you G.E.D. and also I wouldn't mention the part about being an ok student. I don't want to add more to the essay because I don't want you to lose your personal persona and voice in the essay. Good luck with your G.E.D.