Song of Solomon 5:6
"I called him, but he gave me no answer."
Nobody likes the silent treatment. When we are talking to someone and they don't respond it can be extremely frustrating. I've read that "the silent treatment is abuse. Being ignored causes the same chemical reaction in the brain as being physically hurt." It's one thing when we feel that another person is giving us the silent treatment but it's much more serious when we feel that way regarding God. We'd rather think that we are not hearing God rather than conclude that He is not answering. Well, the latter may indeed be the case. He may not be answering and we have to wrestle with understanding the purpose behind His silence.
Sometimes God uses silence to get our attention. Other times there are unconfessed sins that we need to address. His silence also teaches us to trust Him to be the Sovereign God. He's worthy of trust in silence as much as He is when He's speaking loud and clearly. There are yet other times when God is silent as a way to teach us to ask and keep asking.
Just because God is silent does not mean He is deaf. Do not conclude that an unanswered prayer is an unheard prayer. I remember many times as a child when I would be tugging my mother's dress tail trying to get her attention. She may not have responded for several minutes but eventually she would say "child, what do you want?" God works the same way. "The silence of God is a test of faith." Pass the test. Keep asking.