Maybe he discovers some legal loophole in the wizarding world's financial system that allows him to reclaim his inheritance. For example, if there was some improper handling of his family's vault by the goblins at Gringotts, he could use that as a basis to demand his money back.
He could prove that certain people who had access to his funds were misusing them. Perhaps some of the people who were supposed to be safeguarding his family's wealth, like some corrupt Ministry officials or relatives who had access to his vaults, were stealing from him. So, by presenting evidence of this misappropriation, he gets his money back.
Hermione could be the one. With her vast knowledge of the wizarding laws and her sharp intellect, she might dig up some old regulations that prove Harry's right to his money. She would then fight tooth and nail in the wizarding courts or against the goblins at Gringotts to get his money back.
In the fanfic, it could be that Harry has a very smart friend who helps him come up with a clever plan. For example, they might find a loophole in a contract that the person who has Harry's money was using to keep it. So, by exploiting this loophole, Harry is able to legally get his money back. Another possibility is that Harry has some special skills or powers in the story that he uses to his advantage. He could use his charm to persuade the person who owes him money or his intelligence to outwit them in a negotiation.
Harry Potter could use his money to improve Hogwarts in fanfiction. He might donate to renovate old classrooms, buy new equipment for the library or even fund extra - curricular activities for students. After all, he has a strong connection to the school and wants to give back.
In some fanfictions, Harry might hide his money in a secret compartment of his trunk. He could use magic to create a hidden space where no one else can find it.
Maybe he wants to keep it safe from thieves. There could be dark wizards or even some of his schoolmates who might be tempted to steal it.
Perhaps there are some legal barriers. For example, the person who has his money might have some legal justifications for keeping it, at least on the surface.
In some fanfictions, Harry might use extremely powerful and ancient magic. Maybe he discovers a long - lost spell during his adventures that has the power to reverse death. For example, he could find a spell hidden in a forgotten corner of the Hogwarts library that was created by a powerful wizard in the past but was deemed too dangerous to be used.
He probably uses magic. For example, to water the plants, he can use a spell instead of a regular hose. And to fence the ranch, he might use a charm to create a magical barrier that can keep unwanted animals or people out.
Well, Harry Potter fanfiction can make money via merchandise related to the fanfic. For example, if the fanfiction has a unique take on the wizarding world, the author could create things like custom bookmarks, posters or even T - shirts with quotes or characters from their fanfic and sell them. Additionally, some authors offer commissioned fanfiction writing. Fans who want a personalized story set in the Harry Potter universe pay the author for creating it for them.
Well, he might manage his daily life by relying on magic for basic tasks like cooking. He could use spells to clean his place and keep it tidy. Maybe he'd also use magic to grow some food in his small garden if he has one.