There was an issue about this when Lolipop first came out. The work around was to reboot the device a few times and then search for an app that might be causing this. However if you have already checked the volume settings, reinstall Flash Player on the device, that should reset the setting.

i have reinstall it but no change

Sound is controlled by the Android settings.

• Opening the Android settings depends on your model of phone and the Android OS version
• In the Android settings look for a setting called Sounds or Sounds and notifications
• There will be an item called volumes tap that
• Adjust the level of the "Music, video, games and other media".

i can see , but iam not talking about there is no sound on the flashplayer only

in the normal videos there is a sound