God does not hear everyone's prayers. God only hears the prayers of saved believers and the only prayer He hears from non-believers is the prayer unto salvation.
Even all believers prayers are not answered. If they were then you would see miracle upon miracle happen every minute of every day. The Bible say's that if we have the faith of a mustard seed (which is very tiny if you've ever seen a mustard seed) then our faith could move mountains. God is not saying in this passage that if we pray that a mountain would actually move but He's saying that we should have that kind of faith in our hearts knowing that if we are in the center of God's perfect will and we ask anything from him that He will hear and answer our prayers. BUT, this is all only according to his will for our lives. God will not let you win the lottery if you pray and ask Him to let you win, He will not grow a new limb for you. God wants to do things for his believers but He wants our main focus to be on Him and eternity, not things of this earth for we are only here for a little while.
I once read something that states it pretty clear. Compared to eternity, our lives are just a mist. We are only here on this earth for a short time. We better make the best of it. Eternity is a long time.