I am frustrated, depressed. Help me out.

I dont feel like eating or slepping everyday. In the night i dont get sleep and always negative thoughts comes into my mind.I have no exictment in life.I dont feel like doing anything .I am bored of life.sometimes i think what am i doing,why am i doing all this,for whom am i doing and most of the time i feel i dont deserve to live anymore.I was not like this before.I was a good person.But now because of all this thoughts everyone thinks Iam useless,but know i am not wat they think,This depression starts everyday in the morning when i wake up and i am fed up with this things.In the night i feel like to do some bad things like kill someone,do theft, damage something, which i dont want to do,it keeps comming all over me.its like forces me to do those things.everyday i realize after this terrible things happening in my life,i feel guilty.please help me to come out of this .I have planned to take overdose tablets to end this.i think it is the only watly to stop this.help me out .