Anxiety and depression. This situation.

Hello doctor, I'm currently working at IIT Bombay as a project staff. I'm suffering from anxiety and depression from past 5 years. My mind is not working properly. Never feels happy and fresh. My performance is degrading year by year. During my graduation I was in very good condition, but after that I can't concentrate on any of my work. My life have been filled with many negativity and hopelessness. I'm unable to control my thoughts. After two year of service I left my job, and started preparation for engineering services exams, but I performed very badly in exam. Now I also find difficulty in my study. There are lot of failure in my life because of depression or may be because of failure I'm depressed. I don't understand what is happening with me please help me out of this situation.