Clicking Sound but No Start at the turn of key

What is your question?

I bought this van about 2-3 weeks ago. It was doing great until about a week ago. It would start sometimes but at other times, it would not start. Then, as I was driving around town a few days ago, there was like a loud noise coming from under the engine like the fan belt was loose or something. Now, my van will not start at all and I am confused as to what the problem is. Any help would be greatly appreciated.