I think I failed my test. I'm so miserable I want to kill myself.
Oh no, that's extreme. Why did you fail?
I didn't understand the material and was unprepared.
I'm sorry you had a bad experience at the test, but it's nothing to want to actually die over. You should use this as an example to try harder next time.
The test was worth half of our grade, there's no way to make up for all those points I lost.
Suicide is not something to consider because of a bad grade on a test. Talk to your teacher and see if they can help you improve your grade. Don't give up!