"If ye abide in me, and my words abide in you, ye shall ask what ye will, and it shall be done unto you." (John 15:7 KJV) .
The word, abide means to dwell on something or someone; to stay connected with something or someone. In His words, Jesus said if we abide in Him and His words abide in us then we can ask what we will. The secret of this union is that when we abide in Him and His words abide in us, then His will becomes our will. Our wills are granted when they align with the will of God.
The reason for unanswered prayers is mostly because those prayers don't align with the will of God. If we ask according to His will, we will be granted our request. As a child of God, our first priority is to make sure our will aligns with that of God. We achieve this by the abiding process. We must abide in Him through fellowship in prayers, and His words must abide in us through studying of the scriptures. These two exercises produce a will that is in alignment with that of God, and at that point and realm, nothing is impossible to you!
Stay blessed.