You're not a failure!! Success starts with a state of mind. I know that it seems like God isn't listening to you but He is and you have to hope in Him! Somebody said "The man who believes he can do something is probably right, and so is the man who believes he can't."
In your first post you said that all your friends have their prayers answered immediately. How do you know that? Their prayer life may not be as amazing as it seems to you. God says "no" to everyone. You also said in your first post that you can't find the point in praying at night anymore. There is point, even if He is saying no to your prayers! Prayer is taking to God. And the more you talk to somebody, the more you know him.
I'm not sure why God is saying no to so many of your prayers, but it may just be that what you're asking for doesn't align with His will and plan for your life. Or maybe it's just how you're praying? Have you said the sinner's prayer (the prayer when you repent and give your life to Christ to live a life that pleases Him) and meant it? How do you pray and who and what do you pray for? If you don't mind, can you post an example of one of your prayers? Perhaps that will help us identify and fix a possible problem.