Currently Being ModeratedDec 15, 2013 7:42 AM (in response to Richardrsa)
Control-click it and choose Open. Alternatively, open the Security & Privacy pane of System Preferences, click on the General tab, unlock the pane, and set it to allow applications from anywhere.
Currently Being ModeratedDec 15, 2013 7:41 AM (in response to Richardrsa)
Welcome to Apple Support Communities
In fact, you need to download it from the Adobe website > http://get.adobe.com/flashplayer Redownload Flash Player from that website and install it. Restart your Mac after finishing the installation.
If you get a message telling you that you cannot open the installer because it does not come from the Mac App Store, open System Preferences > Security & Privacy > General, press the padlock at the bottom left corner of the window, and choose "Anywhere" under "Allow applications downloaded from". See > http://support.apple.com/kb/HT5290?viewlocale=en_US&locale=en_US