Why did the dionosaure starve to death?

Well Mohd Danish, This is a very good question. Since I am not sure how old you are. I will try to keep my answer simple to help you understand. During the Jurassic period (~213 M years ago) the dinasaurs Flurished. At the end of this time, there is evidence that something dramatic happened. This is believed to be an astroid hitting the earth. The reason why we believe this is evidence. Well when this astroid hit it caused a dramatic and instantanious change in the earth's climate. This change caused many things, such as the food the dinasaurs eat, die off. This caused the dinasaurs to need the food and when they could not find it anymore they died.

I hope this helps.

There are a few theories out there but no one can aboslutely tell you exactly how it all happened, but scientists do know it did happen. Could have been a combination of a few factors. See the following article:
How did the dinosaurs become extinct - extinction of the dinosaurs