When Prettier “doesn’t work,” I try not to touch five settings at once. That usually makes the problem harder to see. Start with one file and ask VS Code a simple question: which formatter is available here?
Run “Format Document With…”. If Prettier is not in the menu, you have a discovery problem: wrong file type, disabled extension, missing plugin, or workspace restrictions. If Prettier is in the menu, choose it once. If the file changes, make Prettier the default formatter for that language. If the file does not change, it may already be formatted, which is easy to overlook.
If you get an error, read it before editing settings. Prettier has to parse the file, so broken syntax can stop it. A bad config can stop it too. So can a plugin that the project expects but has not installed. Another quiet culprit is .prettierignore. If the file is ignored, Prettier is probably obeying the project, not failing.
When I am still unsure, I open the VS Code Output panel and select Prettier. That log is not pretty, but it usually tells you which Prettier version ran, which config it found, and what blocked the format. Guessing is slower.