I now, a lot of people wrote from "Start menu and Cortana not opening in Windows 10". The answer already everywhere was the running "Powershell" with run this command in administrative permission:

Get-AppXPackage -AllUsers | Foreach {Add-AppxPackage -DisableDevelopmentMode -Register "$($_.InstallLocation)\AppXManifest.xml"}

This a good solution for me too, but only the till next restarting. After restart the problem is same! I tried a lot of another suggestions, but if the problem is solved (only a few) then only for the next reboot.

Please check if you have installed Cumulative Update for Windows 10: August 5, 2015

https://support.microsoft.com/en-us/kb/3081424

This update would fix some issues regarding Start Menu

You may create another user account to recheck the issue.

BChris,

Just want to mention that there are new Windows Updates available, please check for Windows Updates under settings and see if there is KB3081438 available. If yes, then update and install it.

If KB3081438 is not installed on the machine, in addition to Windows Update, we may also downlaod and install it manually from Microsoft Update Catalog:

http://catalog.update.microsoft.com/v7/site/Search.aspx?q=KB3081438

Regards