Rebbe Nachman teaches us:
If a person engages in much prayer and conversation with Hashem for many years, and nonetheless sees that one is still very far from Him – and it seems that Hashem, so to speak, is hiding His Face, G-d forbid – the person should not make the mistake, G-d forbid, [of thinking] that Hashem does not hear one’s prayers and conversations with Him at all. Rather, one should believe with perfect emuna (faith) that Hashem hears, listens, and pays attention to every single word of every prayer, request, and conversation. Not a single word is ever lost, G-d forbid.
Adapted from Kitzur Likutey Moharan (Abridged Likutey Moharan), by Rebbe Nosson of Breslov