Can't install and use Flash Player

For the past several weeks, I've been experiencing a kind of nightmare with Flash Player.  I use Firefox and I suddenly couldn't receive/open ecards from a friend.  I checked with Jacquie Lawson ecards who said I needed Flash Player.  I've tried to download FP countless time, no success.  I can't even find it in downloads  I get a message:  "Windows cannot find C:\Users\Ellen\Downlaods\flashplayer19_ha_uninstall.exe." Each time I try the download appears in the download status bar, I click on it, click "Run" and it goes to the Adobe FP install page which says to close the browser.  When I click "close window" to close Firefox, it doesn't close.  I try the download again and click "continue," and the close browser message loops. The Adobe support sight says to try to revert to a previous version, but I don't know how.  Sorry for this long post, but this is so frustrating.  I desparately want to be able to use Flash Player in my system.  Thanks ever so much for any help you can give.  ellenc