Go to Adobe.com - download "uninstall flash player". also download "install flash player" you can locate them in downloads, just use the search box. Then close all browser windows, including all messenger windows, and sign out from these first. then restart your pc, then use uninstall flash player, restart your PC, and use download flash player. Believe me, this is the way to properly install it. Ask adobe they'll agree.
P.S. the 2 downloads will automatically go to your desktop, so you wont have to locate them.