I am sorry but I have to agree with Reverb. This isn't a very great essay.
Some of the mistakes:
"Suicide is what happens when someone kills themselves"
-Suicide isn't what happens when someone kill themselves. It is the action of killing themselves.
"Suicide is among the top three causes of young deaths between the ages 15-34."
-This makes it sound as if the young deaths are aged between 15 and 34
-How is 34 young?
"it's caused by some of these few mental illnesses, or all; depression, bipolar disorder, schizophrenia, and drug use."
-Doesn't make sense. A better sentence would be: it's caused by one or more of these mental illnesses: depression, bipolar disorder, and schizophrenia. Drug use isn't a mental disorder.
"Suicide by young people has been increasing lately, and there's no studies that have shown why"
-Again, this doesn't make sense. A better sentence would be: Suicide in teens has increased dramatically in the past few years.
-There are known reasons why suicide is prevalent in teens; drugs, media, hormones, and stupidity
"Because of the fact that suicide is caused by mental illnesses, there could, or could not be a way to cure it. Suicide is among every race, culture, and sex."
-NEVER start a sentence with "because of the fact that...". It makes you sound really stupid
-I suggest taking the "Suicide is among every race, culture, and sex." It doesn't fit well.
As you can see, I just took every sentence in your first paragraph and made it better. Keep trying and put some more time into it