Why would you want to install such an old version (V8)? I would recommend to install the current version 9,0,115,0.
By the way, on this page, you can see which version you have currently installed.
In case you have problems installing the Flash player, you should perform a complete uninstall of all currently installed plugins and components. Adobe offers a special tool for this. You can find a guide on how to do this, as well as the download link here (Javascript is needed to view this page).