Well all have had those days where they feel like they just don't measure up to others, and trust me, I've had my fair share. But the most important thing to think about is that this feeling will pass eventually.
First, take a breather.
At the moment, it seems like you have nothing going for you. I get it. You may be overwhelmed with school, work, etc. But you should take some time to yourself and think of all the things that you have succeeded in, instead of the things you haven't succeeded in. Take a deep breath and relax. Try to meditate as well.
Know that you have supporters cheering you on.
Everyone at least once feels like no one cares about them, but that isn't true. Someone out there is watching you and saying, " Hey, that girl/boy is pretty awesome at what they do. I'm proud of them and can't wait to see them grow." It could be a family member, teacher, significant other, or even a friend. Someone cares.
You are good enough.
It's as simple as that. You are worth every breathe that you take, and you matter to a lot of people. So, I suggest to write down some things that has improved your life or someone else's life.
And finally, you are not alone.
Yes, just about every post like this says something of that sorts, but it's so true. Thousands, if not millions of people are going through something similar you are going through, and it's okay. If you are having suicidal thoughts or actions please call the suicide hotline number (1-800-273-8255). You are loved, and most importantly; you are enough.