God tells us in 1 John 5:14 that if we ask anything according to his will, he hears us. Not only does he hear us, but he responds. He tell us in John 15:7, if you abide in me, and my words abide in you, ask whatever you wish, and it will be done for you. We must learn to remove the doubt from our minds and to recognize his word as truth, it does not return void.
It is not if God will provide for your bills, but rather when he provides for your bills; not if he will heal you but when he heals you; not if you will get the promotion but when you get the promotion, and so forth. God is only limited in responding to our prayers by our doubts and unwillingness to move from the if statement to the when statement. If you catch yourself saying the "if" statement then stop it and move towards the "when" statement. When God heals me, when God promotes me, when God delivers me all recognize that God will fulfill his promises for your life.
We need to learn to be patient, to trust in His will, and to remain consistent in our belief in His word. We have not because we often ask not and often believe not. As you believe, you shall receive. Accept God's word as truth and His promises will come to pass in your life; not if they come to pass, but rather when they come to pass! Just a little advice to go!