Most of the time I feel sad and nobody wants me around and I don't really want to be around anyone could you tell me why?

Could be depression. You need to be evaluated for the illness of depression. It is characterized by sadness of mood, lack of energy and interests, decreased libido, sleep changes, decreased socialization and worthlessness among other symptoms. It is a very treatable condition. Talk to your doctor about it.
You may be depressed. You may be suffering from major depression, which is treatable. People who are depressed are sometimes irritable, which may cause others to aviod you. Lack of interst and social isolation often occur in depression, as well as low self esteem. You should see a doctor and or mental health care professional for an evaluation.