If your Flash version is 126.96.36.1991 or newer, you will first need to uninstall it using the uninstall_flash_player.exe tool.
(Download, unzip, run it)
Next, remove the "Macromed" folder from your system (c:\Windows\System32\Macromed).
After uninstalling, restart your PC to complete the uninstallation process.
To find an older version of Flash, click here: https://web.archive.org/web/....ayer-versions.html
Press Ctrl+F to bring up the Search function and find version number 363 (recommended) and download the package.
Install this Flash package and ensure it is working in your browser. Make sure you try it in Palemoon or Basilisk as other browsers may prevent Flash from running.
After installation, turn off Automatic Update.
To find which version of Flash you currently have installed, check the Control Panel.