Well, maybe he stumbles around blindly for a while, bumping into things and getting into all sorts of comical situations. He could also rely on his friends more to help him get around until he finds his glasses.
In the fanfiction, when Harry Potter loses his glasses, it could lead to some really interesting character development. For example, his friends might have to step up and protect him more. Also, it could be a chance for him to discover new magical ways to improve his vision without the glasses, perhaps a spell or a potion that he has to search for.
Well, in some fanfictions, Harry might rely on his other senses more acutely. He could use his sense of hearing to detect movements around him. For example, he might be able to tell if someone is approaching by the sound of their footsteps. His sense of touch could also help him navigate his surroundings, like feeling the walls or furniture to figure out where he is.
Well, it could start with Harry being lured into a trap by some mysterious enemies. They might be after the secrets of Dumbledore's Army or something. Once trapped, they start torturing him. His glasses could be lost when he's thrown around during the torture. Then, he might use his magical skills, like his ability to communicate with snakes (which he has from being a Parselmouth), to call for help or find a way to escape. He'd be at a disadvantage without his glasses, but his determination would keep him going.
It could be a group of rogue Death Eaters who think that kidnapping Harry would bring them back into Voldemort's good graces. They might take his glasses as a way to humiliate him, seeing Harry as the symbol of their defeat. They underestimate Harry's resourcefulness even without his glasses.
In a fanfiction, if Harry Potter loses his glasses, the plot will likely take a different turn. His lack of clear vision could make him seem less confident, which would change how others perceive him. Enemies might underestimate him, giving him an opportunity to surprise them. His search for a replacement or a solution to his vision problem could introduce new characters, like an old wizard who specializes in eye - related magic, and new sub - plots could unfold as a result.
In the fanfiction, Shacklebolt could be a key figure in a plot related to Harry losing his glasses. He might be involved in a mystery where the loss of the glasses is more than just a simple accident. He could be investigating whether it was a malicious act by some dark forces, and his role could be to protect Harry and find out the truth behind it. He may also be in a position to teach Harry how to adapt to this new situation without his glasses, using his vast knowledge of magic.
He might start by retracing his steps. He would think about all the places he had been recently and search those areas thoroughly. For example, if he was in the library before losing his glasses, he would go back to the table he was sitting at and look around on the floor and on the bookshelves.
One big challenge would be in his studies. Magic often requires precise wand movements and seeing spells being cast by others clearly. Without his glasses, he could misinterpret what a teacher is demonstrating, and this could affect his learning. Moreover, in Quidditch, he would have a hard time seeing the Snitch or other players clearly, which is crucial for the game.