A plot twist could be that Harry's kidnapping and loss of glasses is the result of a time - travel mishap. A future version of himself (or someone else) accidentally causes the present - day Harry to be kidnapped and lose his glasses. The future version is trying to change the course of events for the better but ends up creating chaos in the present. Harry, without his glasses, has to figure out what's going on and how to fix the time - line while also escaping from his kidnapper. Another twist could be that the kidnapper is actually an undercover Auror gone rogue who is using Harry as a bait to draw out a much larger and more dangerous criminal organization. Harry's glasses are lost in the process, and he has to figure out who to trust among his captors.
A plot twist could be that the person who beats Harry and causes him to lose his glasses is actually under the Imperius Curse and not acting of their own free will. So Harry has to figure out who is controlling this person rather than just seeking revenge on the attacker.
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.
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.
One possible plot twist could be that without his glasses, Harry has a hard time recognizing his captors. It might turn out that they are people he thought he could trust, like some seemingly friendly Hufflepuffs who are actually under the Imperius Curse. This would add an element of betrayal and confusion to the story.
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.
One possible plot twist could be that without his glasses, Harry has trouble recognizing his captors or his surroundings clearly. This could lead to some miscommunications or misunderstandings. For example, he might mistake a friendly wizard trying to rescue him for another captor. Another twist could be that the kidnappers took his glasses to specifically weaken him, as he is so used to seeing the magical world clearly with them. They could be using it as a psychological tactic to make him feel more vulnerable and off - balance.
Well, perhaps Harry could be captured by a group of rogue Death Eaters who still believe in Voldemort's ideology. They torture him to find out if there are any remaining secrets of the Order of the Phoenix. In the process, his glasses get broken or lost. Harry then has to rely on his other senses and magic to try and escape. This could lead to a story of his inner strength and how he overcomes the physical handicap of not having 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.
His friends, Hermione and Ron, would surely help. Hermione with her intelligence and Ron with his loyalty.
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.