I just finish high school a few weeks ago, and me not really caring about the graduation ceremony(still attended though) left my diploma in my mom car and my step dad accidently threw it out and now it in the dumpster. So I want to know if I should seek a replacement from the school or I just not care and focus more on the degrees for college instead.

I'll be honest, while I'm glad I still have mine, I haven't even looked at it in over twenty years now. It's nothing that's going to prevent you from obtaining work in the future. If it bothers you enough, maybe try getting a replacement for the one that's lost, I wouldn't think it would be too hard to do.