Jeremiah 33:3 says, "Call unto me and I will answer thee, and and show thee great and mighty things which thou knowest not."
Malachi 3:6a says, "For I am the Lord, I change not."
In other words, you can trust God. He doesn't change His attitude; He doesn't change His character. He doesn't waffle on His promises. He always keeps His word.
There are some conditions. 1) You must be His child. The first prayer He will hear from you is "Lord, thank you for dying on a cruel cross for my sin. Please forgive me for my sins. I give my heart to you and ask you to be my Lord and Savior. Help me to be more like you." Your life will not magically become perfect and all your problems disappear, but you will have someone with you 24/7 who can help you through anything. Jesus promised never to leave you or forsake you.
2) John 15: 7 is part of a lesson Jesus was teaching. In this verse he says, "If you abide in me and my words abide in you, you shall ask what you will, and it will be done unto you." He follows this with an illustration of fruit abiding in the vine. If you've ever seen a grape vine you know that if you pluck a cluster of grapes they don't continue growing and living after that. They immediately begin the process of dying. Jesus is the source of our life. He is the one that sustains us and teaches us how to live the life he has planned for us. If we read and study his word, the Bible, and memorize it so that it takes root in our heart, it will change the way we think and make decisions. When our thinking and our will begin to line up with his, our and his will coincide. It is at that point that we can ask anything and know he will do what we ask. We will be asking what he wants anyway.
For example, the Bible tells us that God is not willing that any should perish but that all should come to repentnce. When we ask Jesus to work in someone's life it is already his will and he will do it. He will not force them, but he will give them the opportunity to be saved (tell him they are sorry for their sin and ask Jesus to save them from their sin and make them more like him). It will happen in his time, not yours, but he will do what you ask.
If you get lazy in your relationship with the Lord and don't pray except for when you have a problem, he may not answer your prayers. If your children only call you or speak to you when they want something are you going to give them what they want? Neither will God.
More in a couple of days or so.