Never - EVER - underestimate the power of prayer! I am constantly amazed at how God works, and though I shouldn't be surprised when he answers prayer, I still usually stand in awe of His workings regardless. It is arrogant of a person to think that God does not or cannot hear our prayers...He does. Every prayer spoken out loud or silently...He hears. He knows our hearts and minds better than we do. He knows our needs and desires, and He knows what is best for us and (...this is where faith comes in) it may NOT be what we think is best.
As the Bible says,
James 1:5~If any of you lacks wisdom, you should ask God, who gives generously to all without finding fault, and it will be given to you.
James 1:6~But when you ask, you must believe and not doubt, because the one who doubts is like a wave of the sea, blown and tossed by the wind
1 John 5:14~This is the confidence we have in approaching God: that if we ask anything according to his will, he hears us
1 John 5:15~And if we know that he hears us—whatever we ask—we know that we have what we asked of him.
John 15:7~If you remain in me and my words remain in you, ask whatever you wish, and it will be done for you.
Now to him who is able to do immeasurably more than all we ask or imagine, according to his power that is at work within us, to him be glory in the church and in Christ Jesus throughout all generations, for ever and ever! Amen. ~Eph.3:20-21