There's this fic I remember reading... I thought it was Harry/Snape but I'm not actually sure. It might be a Snape-as-mentor story. Anyway, Harry is at the Dursleys and Vernon snaps, I think he gave Harry chemical burns or something similar. Harry ends up blind and deaf and is taken to a Muggle facility to heal. Maybe he's mute? Anyway, he learns sign language and uses pins to coordinate his wardrobe. Snape spends the fic searching for him and trying to win back his trust. Toward the end of the story, there's a scene where Harry's in the greenhouses, with his hands buried in the dirt because he's so sensitive to the flows of magic.
Something like that. Does any of that ring a bell? I thought I'd found it on painless_j's recs, but none of them seem familiar. If anyone recognizes it and can give me a link, I'll be forever grateful!