Where has apes goone?

I have a question. Where have our ancestors, apes, gone?

Why aren't they living now on earth? Why is there missing-link between human kind and monkey?

First I thought they couldn't get used to the environment and disappeared from the earth.

But they came out on the earth 2 million years ago. They had been evolving to human for long long time, which means they had been used to the environment and surviving for million years. Why did they end up disappear? Did every single apes evolve to human kind?

I have no answer right now. I want to look for an answer or hypothesis on the net.