Before you try to install Adobe Flash again make sure that all versions are uninstalled. Most computers have at least 2 installed. Use the free app IObit Uninstaller to scan your PC and thoroughly uninstall anything related to “Adobe Flash” and “Adobe Shockwave”. During the uninstall process the program might take you to an additional “Powerful Scan”, delete everything it finds.
Go through the process again until all versions are uninstalled. Once all versions are uninstalled restart your PC. Last, install the latest version of Adobe Flash.
Here is the free version of IObit Uninstaller: http://portableapps.com/apps/utilities/iobit_uninstaller_portable
Download the latest version of Adobe Flash here: https://get.adobe.com/flashplayer/