Outlook is a tool that comes bundled in Microsoft Office package. This one contains a couple of applications like Word, Excel, PowerPoint, Access and more. If you accidentally removed Outlook from your computer, the only way to restore it is to reinstall the whole package (Microsoft Office). It's possible that you downloaded a corrupted version from the Internet. It's advised to always use official or trusted sources to download and install applications. For more information about Outlook, visit its official website.