How to get out of negative thoughts about life? i am suffering very much due to this.

Dysthymia?: Dysthymia is an on-going low-level of depression which doesn't meet the full symptom threshold of severity for Major Depression, but is still emotionally corrosive and cognitively distorting. Depressive thoughts seem as if they are under an individual's control and they often ask themselves, "Why can't I see the glass as half-full?" Therapy can be a reality-check to distortion.

Psychologist.: Depression is terrible. Hurts both emotionally and physically. Counseling with a psychologist would be your best bet to find a lasting remedy. Medications can help in the short term, but are not an appropriate replacement for counseling. It would help you to identify the source of those negative thoughts. Good luck.