How to install or fix your flash installation in Linux Mint
1. Open Synaptic ; under administration menu
2. Search 'Adobe'
3. find, scroll down to, Adobe Flash Player plugin installer, which is titled 'flashplugin-installer'
4. right click and click 'mark for installation', or double click
5. click 'apply' in the toolbar
if it is already installed, then right click and click re-install
if that doesn't fix it, then check to see what other 'flash' files are installed; scroll down
only 'mint-flashplugin-11' should be installed, uninstall everything else
does this work for you? y/n