There could be a heroic rescue. Maybe her friends or family notice she's missing quickly. They start looking for her and manage to track down the kidnappers. Since she doesn't have her glasses, she has to rely on her other senses like hearing to help her stay alive until she's rescued.
She could use her memory of the environment before she lost her glasses to her advantage. For example, if she knew there was a particular landmark near the place she was kidnapped from, she could try to move in that direction once she escaped the immediate area where she was held.
She might be in real trouble without her glasses. Since she is often the brains of the group, not being able to see clearly could make it hard for her to find a way to escape. Maybe she tries to use her other senses like hearing to figure out where she is.
The kidnapper could be a jealous rival. Maybe in the story's setting, there's a competition of some sort, and the girl without glasses is a threat to the rival. So, the rival decides to kidnap her to eliminate the competition.
She could end up in the wrong part of town. Maybe she was supposed to be at a library but ended up near a noisy construction site because she couldn't read the street signs clearly without her glasses.
One possible plot could be that the girl is kidnapped from a place where she left her glasses behind. She is a key figure in a certain event, and the kidnappers want to use her for their own gain. Without her glasses, she struggles to adapt to the new environment at first. However, as time passes, she befriends another captive who helps her get around. Together, they plan an escape and in the process, she discovers that there's more to her kidnapping than she initially thought.
Perhaps the girl without glasses has a special ability that she's not fully aware of. The kidnappers, who are part of some sort of secret organization, know about this ability. They kidnap her to study her or use her power for their own purposes. As she's held captive, she starts to discover more about this ability herself and tries to use it to escape.
In the fanfiction, the girl without glasses could remember the layout of the house in great detail. Even though she can't see well, her memory serves her. She starts to crawl on the floor to avoid the smoke and uses her memory of the rooms and hallways to make her way towards the exit. Along the way, she might find other survivors and help them as well.
Well, perhaps she jumps in the pool without her glasses because she's in a rush to join her friends. Once in the water, she realizes she can't see clearly but still has a great time playing water games. Later, she might worry about how she'll find her glasses when she gets out.
One possible fanfiction could be that the girl who was kidnapped was a very shy and nearsighted person. Without her glasses, she could barely see. The kidnapper might have targeted her because of some special ability she unknowingly had. As she was squinting in the dark place where she was held, she started to recall all the mystery novels she had read, trying to find a way to escape using the little she could see and her wits.
Well, it could be that the glasses hold some sort of magical power. Maybe a villain kidnaps them to use that power for evil deeds. For example, the glasses might be able to see into other dimensions, and the kidnapper wants to rule those dimensions.