1. Uninstall the existing plugin using
# apt-get autoremove flashplugin-nonfree2. Close all Firefox/Iceweasel windows (must)
3. Download the flash 10 plugin from here (or try this)
4. Use this command to install
#dpkg -i install_flash_player_10_linux.deb5. If you encounter this error
dpkg: error processing adobe-flashplugin (--install):user this to resolve the dependencies
dependency problems - leaving unconfigured
Errors were encountered while processing:
adobe-flashplugin
#apt-get -f install
6.That it check whether flash player has installed correctly here. Also note your version.
Sincere thanks to cyberciti.biz.