Don’t use gnash, it’s not usable yet. Remove it if You Have Installed it from the Following Commands :
sudo apt-get remove gnash
Ways For Installing Flash Player .
1) Download this: http://fpdownload.macromedia.com/get…9_linux.tar.gz
Right-click on it, and extract it. Then, open the terminal and cd to the directory with the files that were just extracted (if you’ll need help on this, let me know). Then do “sudo ./flash_installer” (I don’t remember the exact name of it.. but just do “sudo ./<name>”)
When it asks you for the path – I think you need to give it /usr/lib/mozilla or /usr/lib/firefox, can’t remember which. After that it’ll be done, restart firefox and it should work.
sudo apt-get -y install flashplugin-nonfree