What is wrong with me?

I use to love school,but now I hate it soo much I cry just thinking about it. I'm in year 11 (my last year) I'm suppose to be in school right now but I'm not,instead I'm at home crying and asking this.:( Year 11 is an important year and I feel like I'm gong to fail my GCSE's :'( I haven't got much friends I got about 3 close friends who are never in school. I try to make new friends but it is just hard. Am I going mental?? I'm always sad and angry even though I'm not getting bullied or anything. I just feel like dying and end it all.