I graduated in 1986. Still have my diploma. Actually, it hangs with my "grade school", and my college diplomas in my office. What can I say, I'm sentimental.
Anyway, get in contact with the admin. office at your high school (yeah, maybe they have a web site), and they will send a certified copy of your transcripts, and a diploma if you need it. Might charge a fee. I know SWA wants the SEALED transcripts from college. I forget if they wanted the high school ones. Someone wanted them though, 'cause I have them also.
United?