Try: https://get.adobe.com/flashplayer/

It should be able to detect your operating system automatically. However, I notice that you're using Windows XP - I am not sure if the latest versions of flash will support your operating system since Microsoft is no longer releasing security updates for it.

Yes, this is what I did. I downloaded and installed the latest version, but the Firefox plugin for it is not present.

Then your operating system is probably no longer supported by Adobe.

So that we're not going to keep playing ring-around-the-rosey, then, what is the last supported version for XP and the same with the Firefox plugin? I need to get this back so I can watch youtube videos and toggle the plugin.

Actually, according to Adobe, XP is still supported under version 15: https://get.adobe.com/flashplayer/otherversions/

If that still doesn't work, you can try downloading an archived version of the Adobe website: https://helpx.adobe.com/flash-player/kb/archived-flash-player-versions.html#main_Archived_versions

Just look for the version that last worked for you.

For some unknown reason, after I wrote my last message, the Flash plugin magically appeared in my plugins list. I have no idea about anything with Firefox, anymore.

It is possible that the registry keys that Firefox scan for finding a plugin are missing.

Try to run the Flash installer as Administrator to see if that has effect.

Do you see the Flash plugin (NPSWF32_14_0_0_xxx.dll) in its expected location?

• C:\Windows\System32\Macromed\Flash\