How do I know God answers prayer?

ALL PROFIT FROM THE 'HOW DO I KNOW?' SERIES IS DONATED TO TEARFUND (www.tearfund.org).Why isn't God answering my prayer? This is a question we all ask at some time in our lives. What's the point of praying? If God knows what is going to happen then why pray? And if he knows everything then he knows what I am going to pray before I pray it! Why when we pray for healing are some people healed and not others? How should I pray? When should I pray? What should I pray? These and many other quest...