What do you mean by a radical change? What exactly do you intend of doing? You cant change a personality trait like shyness so easily. And your stutter isn't going away unless you outgrow it. Changing high schools may help with the bullying. Sometimes you're just in the wrong environment. But also high school is just a place where this kind of thing tends to happen. People aren't at their best in life. You're surrounded by people who are immature, can't regulate their emotions or behaviour propery due to underdeveloped frontal lobes. And they tend to lack foresight or thinking about the moral and ethical ramifications of their actuals. They just do shit and say shit without things about how it affects people. The point is that the real world isn't like high school. College or university is different. The workplace is different. In the real world, people could care less about your haircut or your shyness or your stutter. People are just trying to survive and get from one day to the next. People are too busy taking care of their own issues whether that be financial, emotional, relationship issues, mental or physical. We all live in our own bubble. As for this radical change, I think that there are only a few things within your control to change. You can find your diet by cutting out carbs and processed food as much as possible. Start working out and getting in shape if you're not already. Or you could join local sport clubs like fûtbol or basketball. Something you can enjoy and is physical challenging. Then there's finding something that will keep you mind sharp and that's also a hobby. Like learning a new language, learning an instrument or learning to program or building robots.