People have a weird notion that if their prayers are not answered right away, then either Hashem doesn't hear them or the prayers are ignored, Heaven forbid. Nothing could be further from the truth. Not a single syllable goes to waste. Imagine that there's a sky full of transmitters that record every word you say and broadcast them to the Heavenly Throne. But, more thasn you can possibly fathom in your mind, Hashem hears everything, everywhere - He personally and with no static. Just as you don't jump everytime your seven-year-old asks for something, Hashem doesn't necessarily grant our requests on the spot. Remember - Rebbe Natan says that wherever you see deficiency, you'll find insufficient prayer.
Everything we ask for is like an item in a store with a price tag. Our prayers are the currency we use to purchase Divine abundance, both material and spiritual. So, if your request has not yet been fulfilled, it means that you haven't yet paid the whole price. Don't be discouraged - keep praying and you'll see big salvations. I guarantee you that Hashem not only is listening to you, but He loves to listen to you.