I'm assuming you're referring to Flash Player for IE/Edge browser on Windows 10. If so, as of Windows 8 Microsoft embeds Flash Player in Internet Explorer (and Edge on Widows 10) with all updates being released by Microsoft via Windows Update. If Flash Player for IE/Edge was uninstalled/deleted, it was done so under some brute force method as the the Flash Player uninstaller does not remove Flash Player for IE/Edge on these versions of Windows (the Uninstall Flash Player for Windows tech note does states the instructions are not applicable to Windows 8 and above). Unfortunately, Microsoft doesn't provide a standalone installer to re-install Flash Player for IE on Windows 8 and above and Edge on Windows 10. You can try running System File Checker to repair files/permissions: https://support.microsoft.com/en-us/kb/929833
Another possibility is to uninstall previous Windows Updates for Flash Player then run Windows Update again and see if that makes the update available again. Prior to February 2016 Microsoft named Flash Player updates as 'Update for vulnerabilities in Adobe Flash Player in Internet Explorer'. As of February 2016 they refer to is as 'Security Update for Flash Player'. Look for the most recent entry in the list of installed updates, uninstall it, then run Windows Update to see if it shows up. There is no guarantee this will work, just an option.
If these options do not fix the problem, please contact Microsoft customer support or their community forums.