It is very possible that you are dealing with something like ADD, depression (it doesn't mean 'sad', but total lack of motivation is a big symptom), or even some learning challenge you were born with.

This has nothing to do with brains! You can have tons of brain, and still not do well.

Are you unmotivated because you can't follow what is going on, and just gave up? Should you maybe be in a more vocational school where you can be "doing" something and learning at the same time, hands-on stuff?

Actually, it might even go easier on you with the parents and the principal if you do some testing. It's all on paper, no blood tests!

Which reminds me - when was the last time you had a good checkup?

Just look at other possibilities - you may have been fighting an uphill battle that has nothing to do with you.

HUGS!