Life is Over For Me

Why do I always feel sad? My mood goes up and down everyday. Today I feel as if my life is over. I'm not doing anything with my life. I just sit at home watch tv and use the computer. All of my friends are busy except me. I hope I don't have suicide thoughts. My mind is also racing. This is the first time my mind is racing while I am depressed. I don't know what I want to do in life. I can't go to school anymore because I can't concentrate. I want to try to work but my family and friends think I won't be able to handle the pressure of work. I'm so sad. I'm worthless. I don't deserve life. My medications are not working as it should. Therapy is not working. Life is dead for me.  I am so so sad. I think it is not worth living. I'm depressed again. I don't know what to do anymore. I guess I will be unhappy for the holidays.