You know those trust exercises you do in seminars or drama workshops, where you partner up and fall back and hope like heck that the person standing behind you has the welfare of your tailbone at heart? Most of the time they catch you, but if you're not the trusting sort, or this person has let you down before, you'll be hesitant. Eventually, if they don't do something to prove you wrong, you'll just stop trying.
Sometimes being a writer is like that.
I remember reading once that if you ignore your muse, if you don't take the time to write down what She/He/It is telling you when they tell you, after a while they'll stop sharing. They won't tell you about that crazy conversation they overheard between your main character and the love interest. You'll see a burnt stump at the side of the road and it won't be the site of a grisly murder, it'll just be a stump.
That's what happens when you stop listening: your muse stops trusting. And one day, when you really need it, it won't be there, because you let it bruise its tailbone one too many times. That's not a symbiotic relationship. You can't treat it that way and expect it to stick around.
In Heather Sellers' Page After Page, she talks about treating writing like a lover. The more I read of that book, the more I think it's true: you need to give it the same nurturing attention, offer the same trust, that you would in a relationship. Imagine if you stopped listening, stopped acknowledging the words of someone you cared about. In time, your world would become a much quieter place, but not more peaceful, because you'd know in your heart what was missing. That you'd let go of something precious.
One of the biggest favours you can do for yourself as a writer is also one of the simplest: listen. When an idea for your WIP pops into your head, or a colorful description of swimming in a lake during a thunderstorm, or a character that says, "Hey! Come on in, I've got French toast sizzling ..." don't hesitate. Write it down.
And if it's been a long time, and you don't remember what it felt like to have those urges, be patient, and listen. Really listen. Listen for the whisper. It's there. And if you acknowledge it, if you feed it, it will return, slowly but surely.