Feeling down

I just got my grade back and I didn’t do good on a final. It dropped one of my grades down to a B. I had 15 credit hours and one of them was a B, the rest were A’s. I know normally this may not be that big, but my high school grades are less than ideal to begin with so I’m afraid I won’t have a chance. I wasn’t looking for a top 10. Just USC and UMich are my targets but I’m not sure with my hs gpa and now this i don’t think I’ll be accepted.