From MEPIS Documentation Wiki
Basic Flash Information
Adobe Flash is a multimedia platform that is a popular means of adding animation and interactivity to web pages. It is a plugin for the web browser and is installed by default in MEPIS.
Note about the future of flash on linux: In Feb 2012, Adobe announced that it is discontinuing its Flash Player for Linux as a standalone download as of version 11.2. Adobe will continue to provide security updates to the standalone Flash Player 11.2 on Linux for five years after its release (presumably 2017). Newer versions will only be available as part of Google Chrome browser. There are some open source alternatives. Read more at the links at bottom of this page.
Flash Version Test
Test which version your browser is using at: http://www.adobe.com/software/flash/about/. If this doesn't match the version you have installed, check the Troubleshooting section.
The flashplugin-nonfree's plugin can be updated to the latest version in a Konsole with
su -c 'update-flashplugin-nonfree --install --verbose'
Finding what the currently installed Flash version is
strings /usr/lib/flashplugin-nonfree/libflashplayer.so |grep "FlashPlayer_"
From debian-multimedia Repository
Direct from Adobe
flashplayer-mozilla is usually updated to newest flash version very quickly, but if you need the MOST up to date version of flash (or want to test the preview releases), you can download directly from Adobe (http://get.adobe.com/flashplayer/). Copy the libflashplayer.so file to your plugins folder (e.g. /usr/lib/mozilla/plugins); however this will break your use of the update-alternatives feature mentioned in Troubleshooting section.
On MEPIS 11 64-bit you should save the libflashplayer.so to /usr/lib/flashplugin-nonfree/.
If you upgraded MEPIS 8 and lost flash capabilities try this fix:
su -c 'update-alternatives --auto flash-mozilla.so'
If it fails and you then get the error message "No alternatives for flash-mozilla.so.", you probably have a problem with your flash plugin symlinks.
Repairs depend on various factors such as which browser you are using but the libflashplayer.so file in your browser plugins folder (example locations: /home/user/.mozilla/plugins/, /usr/lib/mozilla/plugins/, /usr/lib/firefox/plugins/ and /usr/lib/iceweasel/plugins/) should link to:
which is where the actual file is.
This Command entered in the konsole will attempt to reinstall flashplugin-nonfree and repair the symlinks.
su -c 'apt-get install --reinstall --assume-yes flashplugin-nonfree && update-alternatives --auto flash-mozilla.so && rm -f -r /usr/lib/mozilla/plugins/*flash* && ln -sf /etc/alternatives/flash-mozilla.so /usr/lib/mozilla/plugins/flash-mozilla.so'