I have an old html file, how can I open local html file with flash file on my computer in 2021? Before adobe flash take down, I can open it, it is easy but now I can't open it. Please help
Did you try to google something like "play flash" or "open page with flash"?
Basically just open the page in your browser. Even if it doesn't play the flash content anymore, it might allow you to download it as a new .sfw file to your desktop. Sfw files you can play with a Flash player emulator.
If that isn't working, Browserstack has an online test platform for developers to test how their content behaves in older browsers. That might work.
If that's not working either, you can download an install an older version of a browser and test with that.
If the content is a game, I'd check if it was included in BlueMaxima's Flashpoint.