I downloaded High Sierra (my computer can support it) and when I tried to install it, nothing happened. I thought it may have been a corrupt download, so I tried to get again from the app store, but for some reason the updater thinks I am already running it and won't allow another download.
iMac (27-inch, Late 2013), OS X Mavericks (10.9.5)
Did you download the full installer or an updater? The former is around 5GBs and will download directly to your Application folder. Once there Apple thinks it has been installed. If you wish to re-download it then delete the copy in your Applications folder.
Just so we're all clear, downloading the installer doesn't install the OS. You have to run the installer and click continue on a few screens before it begins the installation.
The App Store only indicates if you have downloaded the installer, not whether you have installed the OS.
Did you click through the installer or did the installer give you a message that it couldn't install.
High sierra downloaded but won't install
