The Mac App Store is a great way to download apps to your Mac, as it takes care of the download, the install, and the post-install clean up for you. Sometimes, however, things can get a bit wonky, whether by accident or design, and you’ll want to go and download an app you think you’ve deleted.
Sometimes the Mac App Store will think the app you’ve deleted is still on your Mac. Or, you’ll want to re-download an app that’s behaving weirdly. When that happens, there will be a “Downloaded,” or “Installed” button there that won’t let you do anything.
While not all Mac App Store apps will work the same way, here are a few things to try out.
First, if your app has been deleted, but the Mac App Store says “Installed,” or “Downloaded,” try this: hold down the Option key when you click on the Purchases tab at the top of the Mac App Store, and, according to this About.com post and a discussion thread on Apple.com, you might see a “Download” or “Install” button instead, depending on how the developers have set the app up in the store.
Of course, if you’ve deleted an app and want to get it back, simply go to the Mac App Store, login with your iTunes ID, and hit the Purchases tab. Even if you’re on a different computer, you can do the same thing. That’s the beauty of the Mac App Store: if you purchase an app on one Mac you own, you can put it on a different Mac you own with a simple login and download.