It's not usually necessary to use extreme measures and uninstall FlashPlayer, but if you do it is probably best to use Adobe's own tool for that.

No doubt preaching to the converted but it is also vital to note that Firefox

• Needs a separate and different Flash Plugin to other browsers (IE & Chrome)
• Current Windows Releases of Firefox are 32bit software

Adobe's FlashPlayer uninstaller may be obtained from this page, which has full instructions on its use (Windows)

• https://helpx.adobe.com/flash-player/kb/uninstall-flash-player-windows.html#main_Download_the_Adobe_Flash_Player_uninstaller

You will need to test and reinstall separately for each browser.

Once it is installed if it does not work first of all try in Firefox's safe mode, if that works you may need to consider in this order

1. Diagnose Firefox issues using Troubleshoot Mode For instance use the Shift key as you start Firefox
   This is just to test. One thing it does is disable Hardware Acceleration.
2. Updating your Graphics Drivers
   Upgrade your graphics drivers to use hardware acceleration and WebGL
3. Disabling Hardware Acceleration
   Troubleshoot extensions, themes and hardware acceleration issues to solve common Firefox problems
   (That could degrade performance)
4. Using an older version of Flash player e.g. Extended Support Release - Flash Player 13.0.0.292
   https://www.adobe.com/products/flashplayer/distribution3.html
   (That could be a Security risk, but the ESR version should be secure although possibly not having identical features)

Further general information

• Install the Flash plugin to view videos, animations and games
• Flash Plugin - Keep it up to date and troubleshoot problems

Yes i did that. When i install it, everything is working well, but if i restart pc it is not working and Adobe test page cannot show me the version of flash player. But plugin is installed.

Problem is solved now. Thanks to this solution.

Great thanks for posting back.

Adobe's software often seems to be problematic, especially FlashPlayer, and whilst some bugs seem to remain unsolved for ever, they do have an impressive Knowledge Base full of useful information, and extensive forum posts.

I will amend the thread title

• Was After flash player update it is not working in firefox 38.0.5
• Now "Flash Player not working: repeated install requests "

You have probably found a less well known solution that many others will find helpful.

You found

• How do I fix Windows permission problems with Flash Player? (Staff post https://forums.adobe.com/message/4323109#4323109 )

  How do I fix Windows permission problems with Flash Player?
  chris.campbell Adobe Employee; l 16-Jun-2015 13:45
  Occasionally users can encounter the following scenarios:
  * After installing Flash Player, everything works correctly until you reboot your computer. After rebooting, web pages ask you to install Flash Player again. This cycle continues over and over.
  * Flash Player works fine for administrator accounts, but Flash content is not available when logging in under a standard Windows account. .... Download the SubInACL Installer from Microsoft

Also congratulations for using good practice and not doing day to day browsing from a Windows OS Admin account.