First of all, let me say that this sounds like a great premise. I wasn't sold on it until the end, but this is the type of book I might like to read. That said, I think your query needs to work harder to sell this story. Here are my thoughts, Hope they help.
In the town of Humming, ninety-nine out of every hundred people are born blind, but with beautiful voices. Then there is the one in every hundred, like eight-year-old Lark, who has sight but no voice. I agree with taylorhale: you need to start with your character. But I believe that you also need to focus on the twist in your story, the fact that no one minds being blind, but not having a voice is the worst handicap. You might say something like, "Eight-year-old Lark is the only one in the town of Humming who can see but she can't talk". Then move into your next line.
In Humming, mute people are bad luck, they are ignored, they are invisible. I would condense this. Make it more concise.
To survive Was she cast out by her family for her deformity? I want to know this., Lark catches and sells songbirds,
that are Look for words like this to cut. (Also, you shouldn't use 'that' after a comma in a relative clause. Use 'which' instead. Read up on restrictive and nonrestrictive relative clauses if you want to dive into the grammar a bit more) coveted not only for their songs, but for their wishes. Every kind of bird carries a different wish; robins are for health, bluebirds for laughter, thrushes for courage, and blackbirds for luck. I would recommend cutting this sentence. Your next sentence does the work for you of explaining why she wants to catch a nightingale.
Only one bird can grant any with under the sun, a nightingale, and Lark has been looking for it all her life. If she catches it, she’ll be able to wish a voice for herself, and
with a voice she’ll be able to enter the yearly Feast of Song, where everyone in Humming competes for a crown and a place in history. 'A place in history' is pretty vague. What does this even mean? You can either expound on this (concisely) or lose the who clause starting from 'where everyone in Humming...'
So when Lark hears a Nightingale’s call in the forest, she risks hunting at night, running from wolves, and even trespassing in another hunter’s territory to catch the bird. It's probably just mean, but this exciting, energetic sentence ends with a clunk with the dull word, 'bird'. Can you come up with something else? Maybe 'to catch her prize' or something?
But the forest hides more than just birds, and when Lark discovers a hidden grave and a diary full of faces Real faces? Or pictures of faces?, she begins to doubt everything she knows about her town and herself.
WISH UPON A BIRD is a MG fantasy novel complete at 60 000 words.