Go to Start / Control Panel / Programs and Features and make sure the Flash Player is listed as one of the installed programs. If it isn't, then it didn't install properly and you should try Mick's answer again (with a clean new download from the site
- not the one you may have already downloaded and saved).
if that doesn't work, let's check your system files:
Go to Start / Program Files / Accessories / Command Prompt and right click on command prompt and click on run as administrator.
Type sfc /scannow (note the space - it's important) and enter and let it run. It will scan and fix some of your system files (if you get errors, post back here). Then try the installation again.
You may also want to login as an administrator to do the installation. Some programs require this and while I don't think that's the case with Flash Player, it can't hurt.
Good luck. Hope this helps.