To reinstall or update your Flash player, start by navigating to the following website: http://get.adobe.com/flashplayer/
That page will automatically identify the browser and OS you're using and offer you a link to download the most recent available version of Flash.
Select "Install Now," open the downloaded install file, and run through the installation process as instructed.
If you're using Chrome, enter the following address into your URL bar: chrome://plugins/
Then, click the "+ Details" button on the top right and scroll down to the Adobe Flash Player section. Ensure that the version with "PepperFlash" in the location string is disabled and that you have only one version of Flash, the one you just downloaded, enabled.
If you're using Firefox, enter the following into your URL bar: https://www.mozilla.org/en-US/plugincheck/
Ensure that the "status" reflects the version of Flash you just downloaded and that your Flash Player is "Up to Date."