I've never seen any distro supply Flash directly. Normally you get it from
http://get.adobe.com/flashplayer/ and follow the instructions (fairly simple). If you haven't done that already, go do it now.
If Flash still doesn't run, and the browser acts as if it wasn't installed, well, I've been there. The install procedure didn't work for me several times, but then I discovered that the .so file for flash, named libflashplayer.so, had to be copied to (or make a symlink) /usr/lib/mozilla/plugins/ (Be not distracted by any apparently more relevant directories such as /usr/lib/firefox-3.5/) The .so file could just as well go in your home directory under ~/.mozilla/plugins/ but then it's user-specific.
With the one libflashplayer.so installed somewhere, you can create symlinks in other places as needed, e.g. /usr/local/lib/opera/plugins/