Since 3-4 months really depressed. hit my head hard on the wall 4-5 times. get angry on petty issues. suggestion please.

Did you hit your: Head on the wall & then become depressed? Or have you been head banging since becoming depressed? Please accept professional help. Let your personal physician know. S/he can evaluate for medical causes of your angry & depressed mood. A consultation to a psychiatrist or pyschology would be appropriate so that you can start working on healing.

Seek help: You should see a mental health professional asap. Don't procrastinate. Seek help.