How can i make myself happy again?

Basically i feel like im a complete **** after someone punished me infront of poeple for something i didnt do, so now some people think im a stupid ****. I feel like a waste of space and there are always obsticles in the way of me getting on and enjoying life.. i always seem to get ill just when something good is going to happen for me, im most probably going to fail my gcses and parents will hate me even more... havent got the motivation to do well...annoyed at people over nothing, crying easily over thins which dont even matter....can anyone help?