Why Won't My Computer Install Adobe Flash Player?
A failed installation of Adobe Flash Player may occur because Flash Player is already installed or because of conflicting open programs. Incomplete download and installation of the Flash installer program can also cause a computer to be unable to install Flash Player.
Adobe Flash Player cannot install if a Web browser such as Internet Explorer, Firefox or Google Chrome is open, so be sure to close all browsers before trying to install Flash.
Check in the computer's downloads folder for the installer program. If it is not found or cannot be opened, try downloading the program again.
The computer may also have permission blocks or security programs that prevent the installation of new programs. These must be disabled prior to installing Flash Player.