I can't find iMovie on my mac any where though it says on the app store it is installed I can not find it to open and use, someone help ?!

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Open a Finder window, select Applications in the sidebar and look for iMovie. Make sure there are no external disks connected, and if so, disconnect them, open the App Store and install iMovie.

You can also use Spotlight to look for iMovie, so press Command and Space keys and type iMovie