keep praying always and realize that not one of your tefillot go to waste. if Hashem didnt answer you the first time you prayed then it wasnt good for you then but that tefilla still did something!
it couldve even saved someone across the world. Keep praying and Hashem will answer when its good for you but each tefilla makes you more worthy of being answered. [maybe in order to be answered you had to pray a certain amount];) may Hashem answer all your tefillot!